Okay I'm very sorry to bother you, but it says I need libnss3
Ok, here should be everything you need, just follow instructions under Ubuntu / Debian-based Linux category
https://www.gbstudio.dev/docs/installation/
EDIT:
In line :
sudo dpkg -i gb-studio_1.0.0_amd64.deb
change the "gb-studio_1.0.0_amd64.deb" to current .deb file name that you have