There were two password managers mentioned in this thread: https://dietpi.com/forum/t/password-manager/933/1
KeeWeb can be run with little effort and adjustments.
Check Self-Hosting at https://github.com/keeweb/keeweb
sysPass looks also promising
https://github.com/nuxsmin/sysPass
https://doc.syspass.org/en/3.0/installing/index.html
Both might be a great addition to the software packages list