corsa

It is a common format for 3D textures in video games and simulators, on both Windows and macOS. I use it when creating liveries for flight simulators and racing simulators on both platforms.

I'd also like to add my vote for implementing a live preview when exporting. As others have stated, as a web dev it is very important to be able to see a live preview along with the estimated file size when choosing a compression level. I'm surprised Affinity Photo doesn't have this functionality, when most of the other image editors I use (although inferior to Affinity Photo in most other ways) all include. Hopefully we see this implemented sooner rather than later.