You will notice that every keypress in evtest is also preceded by a KEY_MSC. This is just the evdev responding to a scancode. If the hwdb has this scancode pre-assigned in 60-keyboard.hwdb then it creates the EV_KEY event that is mapped. What you want to do is turn this EV_MSC into an EV_KEY by mapping the unknown scancode to a evdev event code using the hwdb file.
The arch wiki has a good article on how to map these scancodes and identify what keycode you want to map. It is generic enough that it should work for most distros. Read all of section 2, it goes into specific detail about your question.
https://wiki.archlinux.org/title/Map_scancodes_to_keycodes#Using_udev
If you run sudo dmesg -w
it should tell you the scancodes that each of those events is triggering. You can then create a /etc/udev/hwdb.d/50-my-device.hwdb file to map those scan codes to keycodes.
Here's an example of a .hwdb file I made for Ayaneo handhelds:
## AYANEO DEVICES
evdev:name:AT Translated Set 2 keyboard:dmi:*:svnAYANEO:*
KEYBOARD_KEY_66=f15
KEYBOARD_KEY_67=f16
KEYBOARD_KEY_68=f17
You can find the appropriate evdev:* information by running sudo udevadm test /dev/input/eventX
where eventX is the evdev fd for the device in question. evtest will show you the names.
I'm fairly confident they were referring to the criticism from China FTA, but you'd need to read past the headline for that context so...
I think that's probably a bit of misunderstanding. Nvidia doesn't work right in gamescope due to some missing vulkan extensions. Linux gaming is primarily focused around using gamescope as a compositor, specifically with gaming focused distros. You can see where the idea comes from following that trend.
But also, fuck you Nvidia.