Is screen mirroring only possible on enabled devices? I've owned an LG GX2, LG V20, and an LG G5m out of which the GX2 had a micro USB port to charge and a micro HDMI for video output, and the V20 and G5 had video output through USB type C to HDMI. I've recently got an LG G7 or whatever it's called, and it no longer works. I've read several articles that suggest that with the right combination of cord/adapter that any Android could be mirrored through HDMI to TV. I'm pretty sure I already know the answer just want to be sure.

Sources:

How to Connect Android to TV

How to connect your Android phone or tablet to your HDTV
Mirroring, or MiraCast is actually not fully supported on Android, this has lead Google to build their own mirroring software... 

MiraCast never really worked on Android, there's always a resolution problem because android isn't designed to OutPut video on different resolution's.  

The solution is sort of a screen recorder that utilizes WiFi and software to show the screen recording on a computer or T.V.

I'm sure that it can be enabled on any device that has had MirrorCast  in the past.  

For example, Android 5.1 and up have the option to mirror removed completely while they work on a new version designed for android.  

You can enable the old MirrorCast using some build.prop tweaks, however it's extremely unstable, Hence the removal in the first place.