My wife, because she is spontaneous and cool, saw the gigabyte x570 itx sitting on my screen at different intervals and decided to buy it. I was looking it over and it does only have 2 fan headers usable that I can see. It does have 3 but the stupid chipset fan uses one of them. I'll test it at some point.
Just got mine in. I actually thought it was just one before ordering, but you are right, two headers. Planning on using splitters for case fans.
Given that Buildzoid has stated the Gigabyte board appears to be the clear winner between the 3 announced ITX boards, I think I'm gonna roll with it despite the lack of fan headers. My AIO pump only runs at one speed anyway so I think I'll just connect it straight to the PSU with a SATA power to 4-pin fan adapter.
Are the other ITX boards out yet? My preference was for the ASRock for the thunderbolt 3 support, but saw no mention of it anywhere at launch.