Test the installer on four distros before lunch
Your install script claims to support Ubuntu, Debian, Fedora, and Alpine. You've tested one of them. Create four containers from four marketplace images: ubuntu/24.04, debian/13, Fedora, alpine/3.19: and snapshot each one pristine before the first run. Run the installer, read what broke, restore, run it again. A restore takes seconds, and every run starts from a genuinely clean OS, not from whatever the last run left behind.
The test matrix stops being hardware you maintain and becomes a row of URLs you visit.