Any B550 or X570.... none of them use chipset for second PCIe.
Here try reading this and see if helps you out, I know its a lot to get your head around at the start and can be confusing
https://www.gamersnexus.net/news-pc/3611-amd-a520-chipset-comparison-specsAlso, PCIe Gen 4 specification is quite bandwidth upgrade over PCIe Gen 3.0 specification.
https://imgur.com/I9voCxU X570 has more of everything and is a great overkill/future position.
Hope you find this helpful.