I have a Mi Box and it's brilliant. I only really use it for Kodi though, so it'd be nice to be able to run Kodi on Android TV for a bit cheaper, perhaps on a TV stick (for a different TV).
Can Leanback Launcher be installed on unofficial android TV sticks to make them feel more... official? If so, are there any good sticks out there running 6.0?
I'd consider a Fire Stick if I can install Leanback Launcher on it, I dislike Amazon's skin. I've heard Kodi is a bit slow on it though :/
There are no Android sticks that I have heard of. There are no other devices that aren't Android TV that have the Leanback Launcher. Anything else you buy will not be cheap enough over the MiBox to make it worth the trouble to try and mimic the Android TV experience. The MiBox hits the least expensive Android TV threshold.
Sounds like you're talking about opengapps TV implementation. http://opengapps.org/ has a radial in bottom right of their list called tvstock. How and which I'm not sure
From my experience, shoehorning LL onto a generic device causes more trouble because the other support files are not present outside of official AndroidTV.
Also hope you are running SPMC instead of pure Kodi, many benefits accrue.