Not sure if this still is about installing the QEMU agent, but if so it is relatively simple:
Since using the noVNC viewer is impractical I added the studio code server addon to HA. In there you open up the terminal and run your usual install command e.g.
apt update
apt-get install qemu-guest-agent
After that you enable the agent in Proxmox and reboot HA.
After a bit of reading, it seems that this is no longer about the guest agent, but maybe it will help someone.
Fortunately, this allows me to ask an off-topic question myself:
I set up a new Proxmox server a few days ago. It uses an Asus Prime B550 Plus motherboard with an AMD R5 pro 4650G. My problem is that the “sensors-detect” command is unable to find any MB or CPU sensors.
It seems that Asus doesn’t provide any information about their motherboard chips and the community behind the lm-sensors program has given up on supporting them. Obviously I still want to know the CPU temps and if possible the HBA temps.
Does anyone here have a solution for getting temp readings from an Asus board?