I do not have a lot of things with alpha < 1, or I would just try it. Those 2 properties of PBRMaterial give me the impression that they are independent being boolean, but their code comments make them seem like you would never do both at the same time.
Would another way to represent them, like as custom properties for a Blender exporter, be to have a
Alpha Fresnel dropdown with 3 items: None, Gamma, & Linear?
Also, if someone could point me to a GLB or .babylon which had a material where setting these could have an effect, it would be appreciated. Feels like I am added features in the dark, when it comes to these 2.