Is there a way to have an self-hosted instance that syncs data to hosted instance (so if self-hosted goes down, we switch to use hosted)?

[grb]

@anutrix

an officially supported/maintained method from Bitwarden would be really helpful.

I would suggest that you support the existing featue request:

Redundant Server Backup

Currently, there is no easy way to redundantly backup a Bitwarden homeserver to the Bitwarden’s cloud servers. Having this option would prevent permanent loss of passwords in case one’s homeserver goes down. (Other topics discuss local backups for homeservers, but this has its own pros and cons.)