and you are right
And I Have very serious doubts... At least on Raspberry that SHOULD be possible. We all know that LibreElec Add-ons can run other programs those like Emulators from Kodi GUI.
So everything we need is:
1. Make an SD-Card with both LibreElec and Android side by side;
2. Make a program which will boot Android from the second partition;
3. Make a Kodi add-on which will run that program.
That does not sound easy, but not impossible at all...