I've done (sorta) similar by using syncthing on an old android phone.

It's worked pretty well. of course it just syncs a folder between my devices, but seeing as my desktop and laptop both have to be on, and my desktop is offline, when i was out... i couldn't really sync properly.

so i got the middleman, my old samsung phone, to sync to. it can be turned on all the time, connected to my wifi at home and make sure i always have a place to sync my data to, regardless of what computer i'm using.