Repurpose Vero 4k+?

I’m no longer using the hardware, but I still like its look and form factor.

Would it be possible to repurpose the device, by installing another operating system like home assistant?

Home assistant is not an OS but an application AFAIK.
You can disable the start of Kodi and then use the Vero4k similar to any other Debian Server.
sudo systemctl disable mediacenter