Hetzner doesn't seem to be listed there, but they offer Nextcloud as a service too: https://www.hetzner.com/storage/storage-share
https://www.cis.upenn.edu/~bcpierce/unison/download.html
Personally, I have the stuff I want synced in git (at work, mostly just text files) - and look to combine that with zfs and zfs send - with the new pricing at rsync.net that is looking very attractive.
But that's different from Google drive sync.
Sometimes, I have to wait for a linux port, but the games usually are on sale by then anyway ;).
TLDR selfhosting a NextCloud server on a raspberrypi and sync data between all your devices. You can also sync calendar/tasks/contacts etc
For periodic filesystem backup snapshots I use Restic.
On the other hand I've had plenty of problems of Insync. And the open source solutions are all garbage.
What do you use instead of Google Backup and Sync client? I haven't found something that works like that. The "best" thing I've found is the FUSE Ocaml filesystem (https://github.com/astrada/google-drive-ocamlfuse) but still it is a "mounted" over network filesystem and not a sync-on-change solution. I tried InSync but could not make it work and it is not free, and also the Gnome "mount Google Drive" option, but it is also a "mounted" over network solution.
Other than that and some of the rough edges (random bluetooth issues, random issues after updating, completely broken Android ADB support), I like Linux Mint a lot. I do all my work and play (CS:GO, NFS, Cities Skylines, Hitman) on it, even for games that are not supported by default.