You mean a fullscreen app with controler support like retropi? :D

Or if you want to use the new drive, clone your drive to the new one(using clonezilla for example)

https://eylenburg.github.io/android_comparison.htm This is a nice overview

I thought its not a standalone signal App is it?

As soon as there is a full feature native signal App i would switch to Linux phone. axolotl or Android emulation didnt work for me :/

I allways symlink(ln -s) some folders from my HDD(Pictures, Movies, Documents, Music) since i dont want to have all my home folder on my slow HDD. May this is an Option for you.