Most modern (less than 5 years old) Android smartphones support Project Treble/GSI, which largely reduce the maintenance cost. But that Treble technology is ac

Most modern (less than 5 years old) Android smartphones support Project Treble/GSI, which largely reduce the maintenance cost. But that Treble technology is actually being used by ubports which does Ubuntu Touch using Android drivers, and porting Ubuntu Touch on any modern Android smartphones is quite easy nowadays (assuming you have kernel source code available). It pretty much just requires rebuilding kernel source code with different parameters and that's it.