Mine does (a fenix 7). I think any model that has a heart rate sensor would probably work based on the wiki page. There are certain models that offload sleep tracking to the official app, and I don't think those support sleep tracking in gadgetbridge yet (last I checked this was the case), but the ones that handle it on the watch like mine fully support that too (and you can view stats and a graph in gadgetbridge).

Speaking of the wiki page: https://gadgetbridge.org/basics/topics/garmin/ - there's a lot to parse since so many models apply, but my fenix 7 has had full support aside from live cloud maps in the weather app, and I've been issue-free since last October aside from a couple things they quickly fixed for me after I opened them.

There are 2 main gotchyas:

1. despite the weather sync not requiring the official app (gadgetbridge can sync with breezy weather), the watch stops trying to refresh it if it's been ~3 months since rotating the api key. In the advanced settings you can have gadgetbridge create a new api key for you, but that may break the ability to use the official app (I don't so I went with that).

2. gadgetbridge can't update the firmware or maps, however you can update directly on the watch via wifi, or you can use the PC app (which works great in a libvirt windows vm).