Fossify File Manager: Open Source Replacement to Files by Google on Android

Just checked it on F-droid. Last updated 13 months ago. This is a fork of another project whose creator walked back the FOSS stance of his projects. Forks were immediately produced, but no real work has been done. I'm using two of these apps, and have no real hope that they will be maintained in any meaningful way.

I'd explore these with caution, unless you're looking for near-abandoned projects to adopt, in which case these may be worth your time to look into. What is there looks good, but without active maintenance it's an encroaching storm of security risks.

Been using it since it came out and it works great. It can't handle USB devices though, so the AOSP file manager has to be used for those.