It sounds like you are looking for information on a highly compressed version of Grand Theft Auto V for the PPSSPP emulator.
Before I put together a detailed article, I want to make sure I’m covering exactly what you need, as this specific topic can refer to a few different things:
Fan-made Mods: This usually refers to "GTA: Liberty City Stories" or "Vice City Stories" modified with textures and menus to look like GTA 5.
Highly Compressed Files: This refers to technical guides on how "24MB" archive files are expanded into full games.
Cloud Gaming/Streamers: This refers to tools used to play the actual PC/Console version of GTA 5 on a mobile device.
Which of these topics are you most interested in for the article?
A few legitimate modders have created tech demos that let you walk a character around a single block of a Los Santos-inspired area. These demos are 20-50MB. They are NOT GTA 5—they lack missions, vehicles, voice acting, or the map.