You have to manually install it. Have a look at the HACS page. If I remember right, it is basically:

1. download HACS and make sure, it is in the right folder inside the container
2. restart HA
3. add HACS as an integration

HACS works perfectly for me from a HA container in podman. I know that doesn’t help by itself, but maybe you have a wrong config.

Isn’t this community about unlocking the 15 secrets, mysteries and facts of selfhosting?

The part how they cloud technically access all relevant files, seems easy to me. As mentioned in other comments, just give someone or somewhere you trust your master password.

Virtually impossible, that my dear ones actually can make any use of this. They don’t even know how to use a command line, not to mention how to decrypt a luks partition. In the end, they will get some linux friend to do this, copy all files on a nfts external drive and hook this up to a Windows machine. So glad, I don’t have to experience this monstrosity anymore.

Nguyễn - Vietnam

Bookmarked for further inspiration

To add some points, that I do:

• Proper logging: So I could realize something unusual is going on
• rootless podman container: harder to escalate privileges and gain root
• Apparmor: same, plus it could trigger suspicious log entries