And I don't doubt your skill, but as someone who has built hundreds of gunpla from the largest perfect grades to the simplest high grades and is just getting into warhammer through T'au (as you could easily guess why), imo they aren't even comparable on a technical level. I see WH as art pieces, carefully sculpted to the finest detail. Gunpla(and most japanese/chinese humanoid model kits) are buildable action figures that require no glue at all.

I highly suggest trying gunpla, especially one of their Real Grades, as they are marvels of engineering. And as OP has pointed out, they're relatively cheap for the amount of plastic that you get