Same as you would on MacOS :
- ditch the .deb package because it’s the wrong tool for the job here.
- Squashfs image with encryption
- Set keyring entries and a wrapper script to manage lock/unlock. If you already know the hardware platform of all users, this can even be improved upon
I have no idea why someone would be using Debian packages to distribute something like this though, if that’s the question. Absolutely not going to work well.
A phone seems like an easier solution, but there are VOIP integrations for HA, as well as ways to stream audio through the media player to different devices. I’m not aware of any integration that specifically does paging as you describe, but it would be easy to do with an esp32 board with a speaker.