Thunderbird mail syncing (without paid plan?)
No, the bridge is available for paid plans.
Thunderbird calendar syncing
Nope
Calendar sharing
With a link to anyone: https://proton.me/support/share-calendar-with-proton-users
With Proton users:
https://proton.me/support/share-calendar-with-proton-users
Easy move from google drive to proton drive
Not yet there, something like that is planned.
Sync android photos like google photos
Not sync but backup:
https://proton.me/blog/proton-drive-photo-backup-android
Offline file saving for specific files in proton drive on android
Offline availability in the Proton Drive app exists.
Sync with folder or mount on linux (smb or similar)
Out of the box not. rclone has some support.