1 pam configuration mistake or one programming mistake in it. However if you can comfortably boot a live usb and fix it, and test it in qemu it should be no problem.
Oh look like pam_time exists…
https://askubuntu.com/questions/631569/pre-scheduled-daily-lock-out-periods
https://linux.die.net/man/8/pam_time
https://linux.die.net/man/5/time.conf
Seems minimal enough.
goreleaser to help with the “where can I get the binaries” problem?
Treat the fediverse as a pre 2007ish internet and don’t expect them to be there just focus on making new friends and creating a good space. If successful they might come but don’t put yourself in a position where you require it to use the fediverse.
You could break your system, but maybe a pam module could make your username/pass not work during particular times.
It doesn’t have to be, just structurally people are incentivized to do this