I read that there's a way to have a custom power off screens and also have custom text? Where can I learn more about this if it's true?

looks to risky not worth it lolhttps://gbatemp.net/threads/tutorial-edit-the-homemenu.424449/
This should be it.
Actually the worst that will happen is you brick the homemenu which can be fixed with a9lh and a nand backup you made before messing with the homemenulooks to risky not worth it lol