Im curious would there ever be a category where you do all the secrets bosses? Lets say there is a secret boss in every chapter. Would this be a category eventually? EX: (Jevil, Spamton NEO)

This has been discussed several times, for the time being, no

I'm confused what's the difference between this and all bosses

yeah theres already all bosses / all chapters all bosses

the only difference currently is doing snowgrave instead of main route as queen is not a secret boss and is therefore not required, I.E. an "All Shadow Crystals"

its a cool category on paper but like, the full game isnt quite out, so unless there are multiple ways to quickly get secret bosses like snowgrave that happen to be faster than main route, then this will most likely be a category, maybe even one when 3-5 release, but for now its not that different from all bosses chapter 1 and then snowgrave aside from maybe using jevilstail for spamton neo and berdly