App Request: Firefox Sync

[RealHypnoticOcelot]

Self-hosting Firefox Sync would be great, and adding it to the list of apps would be amazing!
It does seem sort of complicated, there's supposedly not sufficient documentation but it is possible according to this issue comment.

The previous version, syncserver, is unmaintained and unsupported, although I've heard that it technically does still work. syncserver-rs is the version that would need to be added to the sandbox, and does contain instructions on the page to run within a docker container.