I work across multiple computers. My desktop is Arch, my main laptop is a Macbook, and I also have a Framework 13. Normally I use my desktop at home and take the mac for traveling. In all cases, I need access to my files.
I think about my data in terms of tiers. I have stuff I frequently access and stuff I rarely access. My head canon for the first tier is “working set”; that's my documents, music, and project files. The working set should be available and fast. Rarely accessed stuff can live on slow storage or offline.
So for my working set I need a way to reliably sync all that data across multiple devices. For that I use syncthing.