If you want a more advanced file manager, try Material Files. They’ve been revived now. If not, then maybe Amaze File Manager. If you really wanna go crazy, WM Keyboard has a built-in file manager aswell

Oh wait, sorry. Pur.ili doesn’t have a source code. Sorry. Use Mojeek or Marginalia instead

Really? You do not even know Fossify? They got a whole suote of apps! Not just file manager, and they are the most famous FOSS Android app suite beside Proton

LibreCuts for video editing Droid-ify as a lightweight F-Droid client Iris Keyboard as a lightweight yet extremely customizable keyboard Pur.ili as a search engine with its own index OpenNavBar for a fully-customizable navigation bar Fossify File Manager for managing files Prism Gallery for viewing photos and videos Lune as an offline music player Pocket Paint for photo editing and paint CoMaps for navigation GeoLibre as an altermative to Google Earth Yagni Launcher as an Android launcher Pimi Widget for weather widget Offline Translator for translating and OCR

Cutwire seems very good but it’s a bit heavy. I’ve used LibreCuts for a while and it’s very simple but advanced enough for me