I use Cryptomator vaults synched with rclone from my Linux laptop to Google and Onedrive, plus an occasional rclone sync to USB drive.
Discussion
Im not familiar with rclone. Similar to syncthing?
rclone is a mature command line program that supports over 70 cloud storage providers. Runs on Linux, Windows and Mac OS.
I use it for backup purposes, but this also makes the vault data available to my phone via Cryptomator app access to Onedrive (or Google Drive).
Note I have only tested unidirectional sync. That is, as I push from my laptop to cloud, the vaults are accessible on my Android phone, but I never push changes from my phone back to the laptop. rclone would be able to handle it, I just don't do it due to concern on the Cryptomator conflict resolution handling it properly.
In case I do want to push from phone to laptop, I have a dedicated "From_Mobile" vault for that.