The equipment would need to be rated differently. How the signal is sent from the rover to the orbiter would be different, etc. There’s a lot of knowledge that you would need to build up about Mars and having probes on Mars and the logistics of sending data to and from Earth via orbiter that you would need before jumping all the way to sending a large expensive rover to Mars.
That’s interesting about NASA not being allowed to share data. I really wonder how China was able to leap to sending a rover without lots of investment in understanding everything else about it.