Hi,
On developer kit, the 4 type-A ports are from an embedded USB hub connecting to USB3.2 roothub, so ideally the total bandwidth is 10Gbps.
Please note if you connect either port to USB2.0 device, it can achieve only 480Mbps. Here is a relevant topic:
connected more than two usb cameras problem on deepstream-app (Jetson Nano Dev Kit) - #12 by DaneLLL