PCIe x1 slot for network adapter card

The PCIe x1 Graphics Card is a powerful and versatile piece of technology that has revolutionized the world of computer graphics

You could look at something like the C9Z390-series which have four x16 physical slots and one x1 slot

pcie 40 in 30 slot slot and an old 750ti for the host in a gen3 4x 2-AEkey to PCIE X1 Adapter Board Extension Cable Supports PCI-E x1 Riser Adapter

pcie 30 x1 slot List of Motherboards with 2 PCI-Express x1 Slots: ASRock B760M-H, ASRock H610MAC, ASRock B760M-HDV, ASUS ROG Strix B760-A Gaming WiFi,