According to a post by TUM_APISAK over on Twitter, Gigabyte is apparently working on the X570 Aorus Pro AX motherboard based on the X570S chipset. The motherboard and the CPU were validated on CPU-Z which suggests it is close to the release.
The Ryzen 7 5700G APU which was tested with the new motherboard is limited to OEMs, at least for now, but should be coming to retail/e-tail later this year, together with the rest of the Ryzen 5000G APU lineup, including the Ryzen 5600G, and the Ryzen 3 5300G.
The S in the new chipset revision should stand for Silent, meaning that motherboards based on the upcoming X570S chipset could have a lower TDP compared to the standard X570 consumer and enterprise motherboards (11W and 15W), and could be passively cooled.
Hopefully, we will hear more about it soon.