This works with (but I suppose also for other Unity versions):
1) NOT USE: NOT include GLTF/PbrMetallicRoughness.shader in (Edit -> Project Settings -> Graphics) This configuration freeze Unity building in "globalgamemanagers.assets". You had to kill the process and restart Unity Editore.
2) NOT USE: copy GLTF/PbrMetallicRoughness.shader in Assets/Resources directory fix the log error, but the Unity Player not renderer PBR or alpha texture correctly (see previous images on other posts).
3) CORRECT: Create a ShaderVariants (Edit -> Project Settings -> Graphics) Save to Asset and load your shadervariants. Check in Editor Inspector if your shadervariants contains GLTF/PbrMetallicRoughness.shader , if not add it ;-)
NOW ALL WORKS!
Please confirm if my fix is corret and I will close the issue here.