I was surprised that nobody in the reverse engineering world has looked into a modern .abr format.

But recently, I've found a new thingie, some abr converter that was developed recently. Take a look at that: https://github.com/scurest/abrupng
This may work with current abr format. I don't know, I have to check it yet. But I'm sharing it here, it may be useful.

Ah, well, that is based on Gimp's ABR loading code, which is just as limited as ours. It only extracts the brush tips, not the rest of the data.

Oh, it's sad.
So really nobody in the world has reverse engineered modern abr format?

Not that I know of...