Looks great so far
I would also recommend to split it. There is no real benefit to bloat the main application with it. However, drm and kodi might be a problem yes. But in case it won't work you could still use it for everything else, like games and your own drm free movies.
It's another way to feed Hyperion and more possibilities are good?!
As i see you splitted "add new device" and zeroconf? Might be worth to combine them, if you want to add a new device, scan for some seconds and compare the saved list(ip|port) against the results. If no new instances are found, provide the manual input.
Edit2: On the other hand you scan on startup. Hm, i need a hands on
Yeah that's a good point I agree. Hopefully, Kodi does not enable the secure flag at all.
It already scans for ZeroConf device on launch. It discovers ZeroConf device and adds them above the saved ones.