Sharing my findings here as negative feedback is also important. TLDR: Didn’t work; I’m going to try those Crestron panels everyone recommends instead.
I used to program Atlona Velocity control systems as a AV Systems Integrator. Your basic system is a touch panel connected to a “Gateway” or control processor. I noticed that the touch panels are just POE powered Android tablets with a built-in kiosk mode that uses a browser to display the webpage that the processor serves. The hardware is high quality, and you can get them pretty cheap on ebay.
One day when programming a Velocity system, I accidentally pointed the touch panel to a device that was not the processor, and the touch panel displayed the web interface of that different device. Years later I bought an AT-VTP-800 (same model I experienced the behavior with) because I thought this might work for Home Assistant, but on initial tests it does not (anymore?).
Pointing the touch panel to my HA server, I get “controller not found”, possibly because HA does not redirect ‘wrong’ port inquiries to port 8123.
I can point the touch panel to a different web server which does port redirect and get “loading”, but it does not work.
Has anyone had any success / can anyone packet capture a handshake between touch panel and Velocity gateway so we can see what it expects? I don’t think it’s encrypted.
I brought up Home Assistant and a request for touch panel kiosk mode during an HETMA Advisory Board meeting with Atlona. I don’t think anything will come of it, but they took notes. (I brought this up with Extron too, but they specifically said they won’t enable a kiosk mode.)