texture-compression-etc2

ETC2 is the compressed-texture family mandated by OpenGL ES 3.0, so virtually every mobile GPU decodes it natively. It covers RGB, RGBA, and one/two-channel (EAC) data at 4-8× compression, saving both memory and sampling bandwidth.

On desktop, ETC2 support is often emulated or absent - the inverse of the BC picture. That symmetry is why cross-platform WebGPU content pipelines encode textures in both a desktop family (BC) and a mobile family (ETC2 or ASTC) and select at load time.

If your audience skews mobile, the ETC2 availability trend here is the number that tells you whether you can rely on it.