  This is an extended abstract for the Oberwolfach Workshop 2101b
\emph{Geometry, Dynamics and Spectrum of Operators on Discrete Spaces}
organized by David Damanik, Matthias Keller, Tatiana Smirnova-Nagnibeda, and
Felix Pogorzelski. It took place in online format from 3rd to 9th January 2021.
