@Klapo This screensaver hack is quite old and hasn't been tested on nor updated for any firmware version newer than say 5.13.6 or whatever build was when Amazon fist implemented its own "use book cover as screensaver" functionality.
And since bin installers are "model locked" for a reason and installer predates the existence of Kindle Scribe it's expected that installer doesn't 'target' your device.
And this hack requires Python hack that probably also hasn't been updaterd for new devices and probably didn't address the deprecation/ end of life status of Python v2.x
