I would like to preface this by saying that English is not my first language so I ask that you excuse any grammatical errors.
So could a setting conceivably have pike and shot military tactics, but the industrialization of early to mid 19th century England?
I want there to be pikemen, musketeers, people with armor riding around on horses, but also textile mills, industrial levels of iron smelting... The way I am thinking is that pike and shot ended with the introduction of better guns, better cannons, and the invention bayonet. People stopped wearing armor because it didn't work against more powerful guns and it was expensive. With the industrial capacity to create lots of steel and iron, the supposed world would be able to create better and cheaper armor. However, with this industrial capacity, the supposed world would also be able to create better and cheaper guns (just like our own world has), which would defeat the purpose of better armor. Another issue with massed pike and shot formations was the introduction of cannons that could take out files of men. I think this led to linear tactics where only two guys would get hit by a cannonball versus a whole line of them. To counter the first two points, the supposed world could have less potent gunpowder. I thinking something along the lines of "chemical makeup is less powerful" or some hand-waving science-y thing since I don't really want to go to reinvent the periodic table and how atoms and electrons bond and break.
There would be two areas where this explanation can be flawed, rifling and lock-mechanisms. Rifling are just lines in the barrel that spin the bullet to make it go straighter. A society that can invent trains would definitely be able to carve lines into a metal tube. That is something I was unable to find a workaround for.
With regards to lock-mechanisms, many of the guns in the pike and shot era had matchlocks compared to the flintlocks of the Napoleonic era. Having matchlocks would help my "cause" since they are generally slower to reload and more of a hassle to deal with since you need to have a burning piece of match rope lit at all times (anything that can detract from the power of gun helps this "cause"). Flintlocks, on the other hand, are harder to manufacture but are vastly superior because you do not need to have a piece of burning match rope with you and can just pull a trigger and shoot the bullet. However, once again, a society that can develop trains would be able to develop and mass-produce flintlocks, which are only hard to produce in comparison to matchlocks. Flintlock guns were around during the time of pike and shot, but they were more expensive and only given to elite units or cannon guards (since having a piece of lit rope around barrels of gunpowder is dangerous). I do not think that I can say "flint doesn't exist" since flint and steel was an important way for humans to make fire and thus evolve, and removing such a fundamental object might mean that humans are still cavemen or something (butterfly effect idk?).
The last hurdle to overcome is the bayonet. With the introduction of the bayonet, the shot people in a pike and shot formation could have little pikes to ward of horsemen. This made the pike kind of obsolete. I don't know why the bayonet was not invented sooner in history. Because I do not know why this was invented earlier, I cannot come up with ways in the world for it to not come into existence, since I cannot come up with any way in our world that it did not come into existence at an earlier date.
However, there is still some hope. The French employed Cuirassiers (horsemen with armor) to great effect in the Napoleonic wars (early 19th century), and both the French and Prussians employed them in the Franco-Prussian war to moderate degrees of success. The latter was when both countries had industrialized to a certain extent, but they took way higher casualties than early period ones. The French also had Cuirassiers in world war one but they got shot by machine guns, however, that is beyond the scope of the industrialization/ tech level of the proposed world.