First I would like to say excellent job on Vivid Unit OS (Debian 12 - Bookworm): version 20260327, Vivid Unit much faster, cooler and GPSDR++ is working fine.
OS Debian GNU/Linux 11 (bullseye) for any HDMI monitor I connected it was detected but this latest release fails to auto detect HDMI. Is there a fix or am I missing something? Running xrandr only shows Screen 0 : DSI-1. Basic attempts at forcing HDMI failed but my knowledge is limited.
Thanks for reporting this issue.
We have created an issue for this in the GitHub repository: https://github.com/uugear/vivid-unit-os/issues/1
Currently there is a partial fixing available, which makes it possible to output to HDMI device. However the main problem now is that could mess up the DSI display on Vivid Unit. Further investigation and work are needed.
This issue has been fixed in version 20260420.
The OS image can be downloaded here.