that mystery was quite easy to solve via Google.

Searching for "waydroid_x86_64 LineageOS 20.0" leads to a sourceforge page [0] of waydroid with LineageOS builds that have 70-80k downloads per month.

It seems to be popular to be installed on CachyOS, which in turn is the 2nd most popular distro to use Steam (after SteamOS itself), so my guess is that it's a popular setup for gaming...

[0] https://sourceforge.net/projects/waydroid/files/images/syste...