I did a similar thing with all my sheets - run over them with super high grit (400/800) sandpaper once or twice, clean with IPA and paper towels and since then I’ve never had any issues with prints not sticking

I’ve not user Klipper in a long while, but would it not suffice if Klipper knew 'Spool has 100m Filament left, print says it takes 110m, throw an error/require user confirmation to continue '?

Definitely! Mostly looking forward to see how/if other printers (especially Klipper) will support it