[?] HomeAssistant OS with web broswer

I am currently running HA OS on unraid and have 2x 15.6" touchscreens with RaspberryOS desktop used for displaying and control the entities.

I would like to install HA OS on one of the touchscreen Pis instead of unRAID so I can turn of the server and still have control of my home.
I know how to install HA OS on a Pi (had it running in the past).
I want one Pi to run HA OS and a web browser “vieweing” itself (127.0.0.1) and the other Pi will still run just a web browser with RaspberryOS desktop pointing to the 1st one.

My question is how can I install HA OS and a web browser on the same Pi to be used with the touchscreen?

It has not been called Hassio for well over a year. Please stop calling it that, it confuses new users.

You are running Home Assistant OS. HA OS for short.

Hassio is a name that was dropped in January 2020. That install method is as you said in the title, now called Home Assistant OS.

However, you can’t do what you want with that install method. You could do it with the Container install method, but IMO you’re better off with a second Pi - or to leave it on unRAID.

Chaged my OP to from HASSIO to HA OS.

Sad to hear that it can’t be done with HA OS - I am trying to avoid a 3rd Pi.

You could try a supervised install on the pi.

Pretty sure there’s a community guide ‘how to’.

EDIT:

Just found it also but in the Debian 10 guide requirements it is stated that cannot run additional SW in parallel to HA OS supervised (I need some type of desktop and chromium).

The Debian 10 guide is for a headless install (no desktop GUI), which is why I linked to the pi OS guide.

What you want to do is going to be officially unsupported, but there is still community support.