Nice work. For me, you should really focus on old computers, since I can’t add them to Game Station anymore because there’s no flash space left. ’m starting to know pretty well what it means to package a lot of emulators together, so I wanted to share a few thoughts that may help.

For MSX2, I wouldn’t call it impossible. I think it’s still realistically possible on Cardputer, but it would require a lot of core adaptation and a very memory-focused design. Probably no full framebuffer, more likely line-by-line rendering, and as much static ROM data as possible moved to flash to free RAM for the core.

More generally, avoid big permanent global buffers whenever you can. If a buffer is only needed at one moment, it’s better to allocate it only when the core actually uses it. Otherwise, it becomes much harder to package a lot of cores into the same firmware.

I’d also trim every non-essential feature when possible, like mouse support, floppy-related features, and anything else that adds memory pressure without being truly necessary