Quick PSA because I couldn’t find anything to do with this on search results.
Refoss bulbs appear to just be rebranded Meross bulbs. After much fighting to try and get a Refoss MSL120 bulb working in HA with the Refoss integration (spoiler: it isn’t supported) I discovered that it is just a rebranded Meross MSL120.
Resetting the bulb (5 on off cycles) and deleting the Refoss app and installing the Meross app allowed it to be connected to the Meross cloud, and then the Meross LAN integration was able to log into the Meross cloud and retrieve the LAN control key and control the bulb over the LAN. The bulb was also automatically discovered by HA as a Meross bulb when connected to the Meross app.
As far as I can tell, most if not all of the Refoss bulbs are just rebranded Meross bulbs with the same name.
Hope this helps someone!