One of the merits of encrypting your data with OpenPGP using a Yubikey is that the private key to decrypt data is stored offline on the hardware and it will not be hacked online.

When it comes to file synchronization, there are several choices based on free software:

• Set up Nextcloud or Cryptpad instance by yourself: file synchronization service on-premise.
• Run Syncthing on your devices: continuous file synchronization, which is completely decentralized.