Why very few if any games are released on linux which uses unreal.
Its exactly what @Teh_Masterer said, linux is ‘second class citizen’ from the time it was publically available, unlike what they claimed in 2014. (link)
I know a some who had to do refund after promising that they will be able to publish game on linux.
Some game engines which does not even have a linux editor, but the published game works just fine.
Other publically available top engines unity and unigine already has a very good linux editor and option to pack for windows from linux. But in unreal packing for windows is disabled is code.(some dependencies + few codes changes might also be required).
Unity made linux editor much later than unreal but they are coming out of beta with a fully supported release by end of 2021. link
UE4 is not stable on linux but things are looking much better with ue5. May be its time about time that epic release at least a beta epic launcher and alpha UE4-editor binary for linux/ubuntu, looking at how many request were there over the years like this link.
I practically compile linux editor every week, and have copied that compiled UE5 binary to different distros and it works fine.
Metahuman is part of bridge which is just a plugin which work as part of the engine. So for the bridge - metahumans issues it is better to contact Quixel customer support. They have very good support and do respond to queries unlike …here…