Control remote RPI from hassio

Help needed!
I have Hassio running in a VM in Proxmox, and want to be able to send “vcgencmd display_power 0 (or 1)” to a remote rpi (currently running debian), that I have connected to a 23" touchscreen. This in order to turn the display on/off from an automation in HA, so it’s not ON all the time. I have tried using termanal i HA using ssh pi@ “vcgen…”, and can get it to work by typing the ssh password manually, but cannot figure out how to get it to work in HA. Mainly because I really dont understand how to generate the ssh key. It’s prabably also possible using MQTT (already using mosquitto for my sonoffs running tasmota), but I have no clue how to set that up. Any good help out there, or maybe an easier way forward?

I’m recently running two pi4b units on Debian. I just spent some time learning how to install vcgencmd, since Debian does not include it in the 64bit distro. Jens, did you ever resolve your issue? Your post sounds to me like you had vcgencmd running in Debian.