So I've been trying out pcloud, they have a free tier, and on cachyos its working very well. On macOS, it too a bit more work. My issues, and struggles with pcloud seems to be consistent with cloud providers. They either work really well on the Mac (and windows) but not Linux, or really well on Linux but not the Mac.
So to get pcloud working on the mac, you install the application, but you need to lower the security settings allowing 3rd party extensions. The only way to do that is boot into recovery mode, and select it there. Then once you boot up, you can permit pcloud access from the settings-> Privacy & security. A reboot is required again. But wait its not working yet, you need to install macfuse, and allow its extensions to load into macos, and you guessed it, another reboot.
Now I can click the pcloud icon on the menu bar and click "Open Drive". For some reason the mounted drive doesn't show up on the sidebar, like my other cloud drives so I have no way of opening up OnlyOffice, naviating to the pcloud and opening a file. I have to open pcloud, double click the file i want and open it that way. Not a huge issue, but its not ideal. I'll probably look to see what I did wrong, or if there's a configuration I need to adjust.
Either way, I now have an easy way to manage my files across my Mac and Linux setup. Its workable as a short term solution. Proton has mentioned they're working on a Linux app, so ultimately that might be the best long term solution