Mind that you should not use a Pi with SD card for HA. I'm not sure what the official stance is, but: In my peer group failing SD cards were responsible for a vast majority of issues. Causes are probably a mixture of heavy logging and power outages; either from the grid, or user error not shutting down the Pi before disconnecting power.

At our house I run HAOS in a VM (on a beefy server). My wife uses the app on her phone (as do I), and we have a cheap tablet with the app for guests. On the laptops/desktops we also have access to the web UI.

As the article points out, remote access for the phones can be done via the commercial offering or a VPN (as in our case: wireguard on the OpnSense).