Ok, that has to be a little awkward. Croatian based PC Eskpert released a video showcasing two unreleased Z390 motherboards from ASUS. One of the two is a ROG STRIX Z390-I motherboard is in Mini-ITX form factor.
The other is the Z390-A from PRIME series, an ATX form factor mobo. Z390 is the refurbished Z370 chipset with broader support for the upcoming series 9000 Core processors.
Have a peek at the video here.