I was able to get a Python-TK GUI going on the device.
I am using BSP 5.1. I am still not sure what exactly I need in my image if I just want to launch my custom UI and not have the wayland desktop show up.
I believe there’s a systemd service running that auto-starts up the Wayland graphical stack on boot. I’d suggest disabling/modifying this service so the desktop doesn’t start on boot. Then creating a similar systemd service that then launches/starts your UI on boot.