There is a highly stable Undertale Android wrapper that allows you to play the full PC version on your phone using a gamepad.
: A top-tier RPG often compared to Undertale for its deep story and character focus. : A classic tactical RPG. The Legend of Heroes: Trails in the Sky : Renowned for its world-building and narrative depth. undertale psp iso download top
If your goal is to play Undertale on a portable device similar to the PSP, you have excellent (and legal) alternatives. There is a highly stable Undertale Android wrapper
Because of the game's massive popularity, several fan-led homebrew projects have attempted to bring Undertale to the PSP: The Legend of Heroes: Trails in the Sky
: The combat system is mapped to the PSP’s D-pad and face buttons, providing a tactile experience for the "bullet hell" soul segments. Current Status and Availability