Save game location on Ubuntu?

[LunaMoo]

It's probably just a hidden folder, similary to Windows, Linux also hides a lot of it's paths from newbie users browsing stuff via GUI.

Unless flatpack intentionally changes something as this is just a third party build linked on official site, it's not suggested, it's just the only one maintained, but it's still just a third party build that could be changing whatever they want. Recommended method for linux would always be building yourself, since 3rd party builds might have changes they aren't open about like for example using system ffmpeg which by popular demand is maintained, but known to break stuff, they could be changing paths for PPSSPP folders as well.