I had a Pi 4B sitting around, complete with a case that directly connects a 3.5" touchscreen via the GPIO pins.
Initially, my thought was I could use the Pi in a very single-purpose capacity:
A sofa-table touchscreen controller for the lights in my living room. That led me to discover Home Assistant, to flash the Home Assistant image, and I started configuring. I figured I would figure out the touchscreen aspect later. So…
- Home Assistant OS is now installed.
- I’ve configured enough that the stuff I care about all shows up in “Overview”
So is it true that in order to get the touchscreen to work, I actually need to do this instead?
- Flash Raspbian to the Pi
- Configure the touchscreen to work
- Install Home Assistant in a supervised (preferably Kiosk-mode) capacity
From searches and threads (like this and this) it seems that’s my only option. 
I suppose this isn’t TOO much of a setback, if so - I can save files that I’ve configured, and made notes on my configurations so I could re-do them.
But - if there’s a way to get the touchscreen working, since I’ve come this far - that would be preferable.
It seems like this would be a pretty common thing someone might want to do, even if for no other reason than to provide some simple controls right on the Pi host - but additionally seems like a waste to mandate using one Pi to act as server, and then have to buy another Pi to use as a client device… so I’d think developers might have considered this? I’m guessing there must be a native option.
So figured I’d ask to confirm - there’s truly no way to get the Pi 4B touchscreen working from the Home Assistant OS image?