Aves libre is the best Foss app I've used for managing a picture library.
learned about Organic Maps recently and its a really nice (albeit very simple, for now) open street maps client for GPS navigation. The interface is super nice
Material files is by far my favorite file browser app, I've been using it since before I paid much attention to foss vs proprietary
I'm rootless also, but haven't played much with shizuku. I just went and enabled it, I'm curious to see the improvement next time I have lots of updates available!