Can one drive a 200 gr projectile from a .40 case and not get seriously high pressures?
Absolutely.
The OP is asking about driving a 200gr .45 and a 200gr .40 at the speed of 800fps.
If you think about it, it should be obvious that is actually a fairly low speed (and a low pressure) for either round.
800fps is near the top end range for .45 acp 200gr lead swc target loads. And, that's because of a desire for a target load, not the gun's capacity for pressure.
.45acp 200gr JHP loads top out in the 900-1000fps fps range, at standard pressure. (from a 5" Govt model).
Certainly the .40 can be loaded to a 200gr at 800fps.
None of my manuals show the .40 SW and a 200 gr bullet, loads stop at 180.
The Hornady 7th edition (2007) lists 200gr bullet .40 S&W loads. Three different jacketed bullets and eight different powders. The data exists, you just need to find a more recent manual that lists it.
Remember, reloading manuals do not list every possible bullet or powder, most list what is expected to be most popular or loads with the bullets they make. And the most focus is on full power loadings.
Generally speaking, when two objects of different sizes are pushed into soft medium with the same force the one with less surface area will penetrate more.
Tip shape is a factor as well. An extreme example would be "its easier to poke a hole with a knitting needle than a baseball bat".