Improve HVM documentation regarding resolution

The documentation is very brief on the use of HVM. My main purpose: I am looking for a way to use a separate screen, displaying in full screen mode the contents of my HVM. Performance is not important. By default, the HVM window s to small to show on a 4k monitor. Inside the HVM, the max resolution is 1080p. I browsed the forums for hours and I came to several options:

Option 1: use xrandr inside the HVM to increase the resolution and make it as big as possible to fit the screen. To do this, I need to increase my resolution but as soon as I go over a certain value with xrandr, the screen is black. This indicates that there is not enough video memory available for the vGPU.How do you increase the vmemory (the video memory) of a HVM Qube? [stackoverflow issue]
Option 2: Graphic card passtrough: I know that VGA/graphic card PCI passtrough is a pain, needs a lot of expertise and configuration (for example, editing the grub). Is a solution for this a USB to HDMI converter (like this), plugged into a USB controller? The entire USB controller can be in PCI passtrough (only the USB itself may not work always as indicated in many forum posts). I am just thinking out loud.
Option 3 (which screws your security completely): install VNC server, enable the HVM in "provides network" option, use another qube (AppVM), set the network to the HVM and install a VNC client. Connect to the HVM. I want to avoid that, because a lot of things can go wrong with that configuration. For example, VNC has a max password of 8.

If someone can help/clarify this, I will contribute to the documentation.

QubesOS / qubes-issues

Improve HVM documentation regarding resolution #4882