Okay, lots of other comments I didn’t read, and this might have been mentioned.
👏Syncthing👏
You mentioned OneDrive. I also jumped around storage solutions as I explored the FOSS world, and nothing hold a candle to Syncthing (in my opinion, but I want/need to try nextCloud). I won’t drone on about it, but if you’re looking to ditch another big data company that’s probably scraping your files, check out Syncthing
Look up Syncthing and then never stop trying to replace closed source and paid software/services. Like any time you launch something ask yourself “does this hit the same way as when I swapped to Syncthing?” If the answer is no you then put “[name of thing you want to replace] foss alternative” into your search engine of choice. You’ll end up down so many rabbit holes, but you’ll come out the other side a whole lot better at making your technology work for you, not the company that made it, and with a suite of free open sourced tools you are in complete control of.
Here are some tools I use that are super easy to get going.
Those are the ones that got me going and I personally believe act as a solid core. Most people will find all of those useful. Other services are more user specific, but that’s a lightweight bundle of software that your RPi will handle well. Much more and you might want to look at beefier hardware.