I’ve been a libretro user for many years now. I love how comprehensive and flexible it is, even though it can be a bit hard to learn for non-techies. And I really like the more user friendly direction it is taking, with notifications, a simple quick menu and so on.
And on that note, I have a suggestion. I have set up a couple handheld systems for my young kids to play retro games, and for the most part this works fine. They rarely have to enter the libretro menus, which would most likely confuse them. But the complex save state functionality is keeping them from saving their games and investing time in longer gaming experiences. Right now it is too abstract for them, and if they understood all the key presses - they would need to memorize what each save slot stores which sounds a bit too much to ask even of an adult.
Have you considered creating a simple save screen similar to the mini consoles, with four screenshot boxes each holding a save state? A couple of the libretro emulators on my Vita feature those, and they are really great to use (CATSFC-libretro-vita is one example). So maybe this feature is in already?
Also, if there was a way to automatically save the game state at exit, and then load it back on game startup that would be great!
Cheers!