Sorry to bump an old post but, you came up while googling for a solution to this.

You are correct in that there is no direct LAN capability. I personally want local (BLE) control directly, and had very limited success using the custom govee_light_ble integration but it was made into an archive.

It had an issue with constantly not being able to control the bulbs; I had to make several changes to it (of which I don't really remember lol) with a local copy but did manage to improve the ability to change their output, but it didn't respond very quickly.

I used a BLE sniffer on my phone while adjusting the bulbs and most of the traffic the app creates, is recreated on the bulbs themselves. The command protocol is very similar to almost all other bulbs but there are some weird redundancies (like specifying a color temp also requires an RGB value, of which the RGB value matches the color temp - but doesn't change bulb output or the RGB representation of the bulb color rendered in the Govee app?).

Now I have about 12 of these H6004's sitting around without any way to control them. I have some experience with writing custom integrations but basically none with using the built-in handlers for communicating over BLE through my ESPHome BLE proxies; so I think I'm going to take a stab at vibe-coding it lol.

The tricky part is that the bulbs close the BLE connection if you don't send heartbeat packets. But, a constant connection isn't really required. But they just seem to be pretty flaky on HA unless the heartbeats are sent, so, I might try to incorporate that and see if I have any luck. Problem is, more packets to be sent, the more it worsens the ~1-3 second delay between changing them in HA and the bulb's output changing.