No, nothing yet. I’m pretty sure that would let fast tool changes work via Octoprint, but I really don’t recommend it. Allowing tool changes at any time could have some gnarly effects. (Especially if the extruders are parked!)
Again, I think trying to enable host mode is more promising. But then we need to do testing of the interactivity between the screen and the server when commands are executed in parallel from them.
I’m very curious how M600 works in that case. I’d like to see the normal screen filament routine kick in, so you can program filament swaps into prints and get the extruder controls to pop up.