There is another similar thread on this topic: Support Other Textures in GLTFLoader.
The official way to support Basis Universal in glTF is to use KTX2. See here: https://github.com/KhronosGroup/glTF/pull/1612
I am already working on the implementations for Babylon, but they will take some time to finish as there are issues with the KTX2 libraries at the moment.