It works pretty well actually! I love FF sync and I started self hosting it earlier this year. You can find the full details (also changes needed in the browser settings) here: https://thesmarthomejourney.com/2023/03/18/self-hosting-fire...
I only wish they would make their new rust based server available via docker(-compose) too. I have not found a working version of that yet
I was looking at this recently and still couldn’t make it work smoothly. The server itself is fine but I couldn’t get Firefox to pick up the new sync server url from about:config.
Possibly my fault and I need to poke at it a little more but in general I can start a docker container just fine so I feel like its maybe not quite there yet.