@Rectus_SA as I did not know which other apps may use OpenXR I ended up trying The Blue (VR game) and it allowed me to acces the menu dashboard and I guess it worked as expected (as settings changes were having an effect on the look of the passtrhough)
So this is a temporary relief, but now the question arise of what could be happening that the DefaultVR Template from UE with those changes from Varjo does not effectively enable and use xr.OpenXREnvironmentBlendMode
I check the log out of curiosity, and it is pretty much identical to the previous one…
