I use one called X-Plore. It’s actually very good. Even has a WiFi server, conpressed archive support, etc. but the downsides are that it’s close sourced and some features are behind a paywall (though IMO they are worth it).
So I was thinking of moving to some free or open source software. Any recommendations?
This one is really great and does everything you expect from a file manager. I’ve been using it for years. But yes, it’s not FOSS.