The "PlayStation Portable Simulator Suitable for Playing Portably" is a multi-platform, open-source emulator written in C++ with the aim of speed and portability. It can run PSP games in full HD resolution with upscaling textures to reduce bluriness and most games are playable. Its development is ongoing and still in beta state, though does have a Switch port and libretro core.
Last Stable Release:
Windows: XP+ (recommended Windows 7+) & OpenGL 2.0+
Linux: Requires SDL2 installed
Mac: macOS 10.7+ (requires SDL2; install via Homebrew)
Android: 1 GHz+ & 2.3+ (requires Unknown Sources to be enabled)