For backups I use a backup HDD and a local server. For a 4th off-site backup I will use proton drive or even Google drive but I always encrypt before uploading. One of the reasons I like picocrypt so much. So tiny it's easy to store a spare copy with your files to decrypt later.

File sharing is usually through wormhole or onionshare. If this is a team member where it's going to be often then we'll share a nextcloud instance.