The best use of your genetically engineered creature would be considerably less exciting than supersoldier but entirely more practical: area denial
Let's review the pros and cons of any genetically engineered attack animal:
- Can kill people without input from a human handler (guns usually require someone to pull the trigger)
- Can self-replicate on their own (guns, the last time I checked, do not reproduce)
- Do not require a modern tech base to repair. Severe injuries or disease might require hospitalization, but minor damage they can potentially heal on their own
- Does not require ammunition
- Are able to sense things humans cannot
- Can more more swiftly and silently than any human, especially a soldier loaded up with equipment
- Can survive in environments that humans cannot
- Can maintain itself in fighting condition if left alone in an environment with sufficient resources (i.e., it can hunt and feed itself if let loose in a forest, a gun would rapidly rust or become unusable)
- Have to be fed and cared for, and will die if you do not (a gun only has to be cleaned)
- Take a significant amount of time to grow to a useable size. Even the dinosaurs, who grew freakishly fast by most modern standards due to having a warm-blooded metabolism yet hatching from eggs, still took about 5-6 years to grow to a size where they could be threatening to humans (and a side effect the more you increase growth rate the expensive and resource-intensive they are to feed, Tyrannosaurus rex is thought to have gained at least 4.5 lbs of mass per day during its periods of highest growth. Mammals are kind of the same way, though their max size isn't as big. Cold-blooded animals like crocodilians actually grow slower than warm-blooded ones. By contrast, a gun can be assembled in a factory in a fraction of that time.
- Both the animal and the human handler have to be trained in order for them to work (by contrast, a soldier just has to be trained to shoot)
- Can easily turn on and kill the handler (much harder for a gun to do this). Will eat you if not properly fed.
- Can only fight in melee (if you try to have them fight alongside soldiers they are liable to shoot their attack animals)
- Can easily be shot and killed (this isn't to say that human soldier's can't, but...). Modern military weaponry is crazy OP compared to most natural weapons, and even if your engineered dinosaur is nothing but a morale booster your solder's morale is going to go through the floor the minute your super-dino is hit with an RPG.
The problem with any genetically engineered attack animal is that you run into the criticism made by this video with regards to Jurassic World's Indoraptor: if you have an attack animal that responds to a laser sight like those on the end of a gun, it's almost always easier and less complicated to shoot them with the gun than sic the attack animal on them.
Given all of these factors, what would be the best use of a genetically-engineered superpredator? Simple, area denial. Release a bunch of your Wani into whatever environment you don't want people walking through and let nature handle the rest. The Wani can hunt and fend for themselves, and all you have to do is make sure they have enough food to survive and are successfully reproducing. Beyond that they require little to no maintenance. They will continue to kill people on their own, and will do so more effectively because they don't have humans slowing them down or revealing their position. Because they can reproduce on their own you essentially have a permanently regenerating minefield that you can walk through without harm.
You can engineer the Wani to respond to certain scents or stimuli so that they don't attack your own soldiers. You can put out feeding stations that give them free food, which not only protects them from starvation but can be used to train them to do what you want, and creates a way for you to easily check on them.
Few people would want to go into an area infested with a bunch of faux-Indoraptors. Modern military units aren't very troubled by apex predators, but that's because apex predators are optimized for efficiently killing prey and surviving rather than straight up combat (and humans with guns are so new they are still an out-of-context problem in evolutionary terms). You could easily design an animal that is a threat to modern military units through genetic engineering. Now all of a sudden any military unit that wants to go through an area stocked with Wani has to worry about being guerilla attacked by enemies that do not require supply lines and have them surrounded on all sides. Such a thing would be made worse if your own troops in the area, you have the direct threat of the military unit coming to engage yours but you also have the Wani which can easily attack from your flanks and back while you are occupied with the human troops.
One potential flaw in this is with the increasing military reliance on drones and less use of "boots on the ground" human troops the Wani might prove less of a threat. The Wani might find it hard to hunt machines over humans and unlike many drones the Wani can't fly.
The idea of intentionally establishing invasive populations of military-grade genetically engineered species for the purposes of warfare is a rather horrifying idea, as could potentially lead to things like genetically engineered superpredators designed for combat outcompeting the local predators and destroying the local prey base, or entire regions of the planet being rendered uninhabitable to humans by cross-bred hybrids between kudzu and poison ivy that unleash a lethal neurotoxin on contact designed for area denial, but it's not much different from how humans have already abused prior scientific discoveries (not to mention already existing fears of biological warfare).
One massive downside to unleashing military grade attack animals to establish a breeding population is that all of a sudden it is no longer safe for civilians to go into the woods (or swamp, or desert, or wherever this is). Any creature that can pose a credible threat to an armed military unit would shred hunters, hikers, and other people who try to go out in the wilderness (not to mention what would happen if these creatures tried to establish themselves in urban areas). Modern apex predators like bears aren't much of a threat because you can kill them with rifles, but if you need military-grade hardware to take them down it's a bigger problem.
A modern analogue might be Pablo Escobar's former hippo herd in Colombia. Pablo Escobar had built a zoo with his vast drug money, and when the authorities arrested him and confiscated his things the hippos were left behind and got out. Now there are about 80 hippopotamuses swimming around the Magdalena River in Colombia, and people are a bit leery about what is going to happen because hippos are known to be extremely dangerous.
As a bonus for the story side of your equation, you have a ready-made "pit of man-eating whatevers" to dispose of witnesses or evidence or for your villains to lower protagonists into menacingly.