Use CoreELEC tool ceemmc-x
Use option to make a copy of internal
Then option remove CoreELEC from internal
Then reflash Android firmware
Now clean install 22 on external media
Use CoreELEC tool again
Option to write to internal as single boot.
Then copy over your addons/usr/data from saved copy you made.
Reboot
Should see message addons are migrating…
This is method i would use.
Does not mean there is no other way