Ok. The PSU should be enough for a 1060 3gb, but the 570 requires a 500w. It should power the 570, but if possible I'd use the GTX 1060.
B365 is quite sparse elsewhere as well since it gets overshadowed by the more mainstream 14nm (and expensive) Z390 chipset that is also 9th gen compatible out of the box.
I would avoid the B365M-K since it only has 2 memory slots and a rather weak vrm situation unless you are budget constrained. I would pick the Asrock B365M Pro4 since it has a decent price tag and decent functionality including 2 m.2s, a decent set of outputs, and a decent heatsyncs situation. The B365 chipset limits your memory speed to 2666mhz and no overclocking, although the 9400f is locked anyhow.
Just curious how much does a...