As someone else mentioned, Charles Stross had an entertaining and detailed look at how dragons would fare in modern warfare, though his "dragons" don't have that much in common with traditional fantasy dragons - instead, they're magical creatures deliberately evolved into their roles, controlled by geas and fed with the souls of slaves and enemies by their psychopathic-elf masters.
There's also Sword Brother by David Weber, which pits a demonic-dragon against an american APC armed with a machine gun. That one is a lot closer to traditional fantasy, while still taking a detailed look at how modern military weapons and training would fare against magic.
The problem here is that there isn't really a way to combine dragons with modern warfare, unless - as you've done - you use "magic" to overcome their fundamental limitations.
First: physics. The largest flying animal known was the Quetzalcoatlus.
https://en.wikipedia.org/wiki/Quetzalcoatlus
And that's about the same size as the dragons you've proposed - and they do the "short hop and glide" style of flying you've proposed.
But, modelling suggested they only weighed up to 200kg, or roughly the same as two fully laden infantrymen. And the general rule of thumb seems to be that an flying animal can only carry around a third of it's weight; I haven't researched it, but I strongly suspect that an animal designed for "gliding" flight is probably going to be able to carry even less.
Overall, this means they have no real carrying capacity.
Then too, armour/skin capable of blocking conventional weaponry is heavy. E.g. a level 4 vest capable of stopping most armour piercing rifle-fire weighs around 15kg. Scale that up to something the size of a horse/dragon, and you're probably looking at 60-100kg. Which means that if your dragons are meant to fly, they can't have thick skin, and your "ablative" armour concept is definitely a no-go.
And that leaves you with a dilemma: either you drape them in armour (as per medieval horses) and weigh them down too much for flying, or you leave them unarmoured and easily wounded with conventional weapons.
And they'll also be slow - the Quetzalcoatlus probably topped out at about 80mph. And if they glide-fly, that suggests their muscle power is limited which in turn suggests their manouvering capabilities will be low. So they'll be easy targets for ground-based AA fire.
Then there's the question as their biology. First: their intelligence and their "trainability". In general, reptiles and birds are less "intelligent" than mammals; the former are cold blooded and don't have the energy to spare, and birds are warm blooded but have smaller brains. Overall, they're significantly less trainable than an equivalent mammal.
To be fair, birds can be trainable - e.g. crows, parrots. But whether they could be trained to "military" levels is debatable - and as anyone who's tried to train
a cat will know, the fact that an animal is capable of learning something, doesn't necessarily mean it wants to, or that it'll be willing to perform on demand.
Then there's their physiology. Are your dragons warm blooded or cold blooded? If they're warm blooded, then they'll probably be more intelligent, and more active. But they'll also need a lot more food. And I'm guessing your dragons will be carnivores, so your human soldiers will need to carry around a lot of meat for them.
Equally, if they're cold blooded, they're going to be sluggish most of the time (especially at night), and will probably need long periods of rest and digestion.
As a guide: a komodo dragon can eat up to 80%(!) of it's body weight in a single sitting, which'd translate to about 150kg of meat for your dragon. Admittedly, the komodo dragon then potentially doesn't need to eat for a month, but it does then need a few days to digest. Which doesn't lend itself well to something being used as a weapon of war.
Still, I suppose you could feed human bodies to them, but that opens a large and controversial can of worms, unless you're engaged in total annihilation of the enemy. And even then, what happens if you get stuck in a siege situation? "Sorry Bob, you're today's dragon feeder. Here's a saw; there might be some shooting later, so you might want to take your other leg off and keep both arms...".
Any which way you cut it, feeding your dragons is going to be a logistical nightmare, far more so than horses (which can generally graze on wild flora when all else fails) and dogs (which are omnivores and require less food than humans).
And then, there's their fighting ability. Teeth and claws: great at short range, but you really shouldn't bring them to a gun fight, especially if you're effectively unarmoured.
Fire-breath (or your magic-nano-tech equivalent thereof. And how exactly do you reload a dragon with this stuff?). Range on this is going to be limited - the M1A1 flamethrower is limited to about 40m range, and despite the name, it doesn't throw fire. Instead, it throws napalm, aka the modern equivalent to greek fire: a viscous flammable liquid which will stick to anything it touches and continue to burn.
Then too, according to Wikipedia, the M1A1 carries about 40lb of fuel, and burns it at a rate of 0.5 gallons per second. Which I think works out at about 5 seconds of continual firing.
Put simply, your "nano-fire" doesn't have the mass to carry any distance, and won't stick-burn. Plus, a dragon won't have the carrying capacity for any significant amount of fuel, and it's debatable whether it'll be able to generate the pressures needed to attack anything more than a couple of meters away.
Finally, there's the time needed to birth, grow and train your dragon.
To use the Komodo dragon as an example, it takes around 8 months for the eggs to hatch, and then another 2-3 years before they become big enough to be considered an adult. And they'll need to be trained, exercised and fed for all of those years before becoming useful.
https://kids.britannica.com/students/article/Komodo-dragon/
By way of comparison, during WW2, the US army produced over 10,000 tanks in 1942 alone, and the training for an M1 crewman is 15 weeks.
Put simply, your dragons are useless for attacking (no armour, short range weapons) and useless for scouting (large, unarmoured, slow moving). Oh, and they need significant amounts of food, take years to mature, can't be mass-produced, and will need human handlers when on the battlefield.
Overall, if you're trying to apply real-world physics to your dragons, you'll have to seriously tilt things in their favour with yet more "magic science technobabble" to make them even vaguely useful in a modern context. But at that point, they're a dragon in name only...
