How to use compressed KTX format of skyboxes?

I’ve put together a playground where you can see it break once I request compressed textures for skyboxes, regardless of whether the KTX files are there or not.

Does anyone know how I can make skyboxes compressed on devices like the iPhone?

pinging our experts @bghgary and @Drigax

Are you talking about KTX2 or KTX1? KTX2 is experimental and I don’t think skyboxes work with it yet.

What about KTX1 ? This is just a skybox, 6 different images like this:

KTX1 should work, but I’ve never tried it myself. Perhaps use Basis?