I’m already down to about 16 gigs available on my internal drive, just from installing applications. I recall seeing one flatpak that was over 800 megs to download and 500 or so installed. (I didn’t keep that one.)
About the screen protector, I believe Purism said a while back that it was only there to prevent scratching while shipping from the factory, and wasn’t meant to be permanently applied. Although I’m still using mine after almost 4 months. Maybe they decided to pull them off before final shipping?