Steve,
Here are some points specific to my Raspberry pi-4 Nexus-DRX install that may be of interest:
I installed Bullseye on the Rpi-4 as a stand alone system before installing it in the Nexus-DRX stack and running your program. I'm using a 64GB SanDisk USB 3.1 flash drive.
I use a DVI only monitor with an HDMI to DVI cable and a HDMI to mini HDMI adapter.
I've also installed Barrier so I can use the keyboard and mouse on one computer for both monitors. VNC works fine as well.
The Rpi-4 (8GB) was originally in a case with a fan and has a heat sink on each chip.
The vcgencmd command you referred to gives a CPU temperature of 48^ C at idle which is surprisingly close to my measurement using a handheld thermometer with a laser pointer.
Is there a way to remove the VNC server icon from the panel?
David
N7NTN