Learning curve for Z7/Z6

I don't think there is anything unique for mirrorless outside of programming options. Exposure Delay mode can be set with the iMenu or a programmed Function key rather than a dial. It also provides more options for short delays related to eliminating shutter shock or touching the camera or cable.

On the DSLR, the timer did not raise the mirror and use the electronic shutter unless you were using LiveView.

My understanding is there is still potential for shutter shock on the Z6/Z7. There are some cases where it has been problematic. Shutter shock is a problem with the mechanical shutter, so the consensus is to only use the Mechanical Shutter at 1/2000 sec or higher unless you have another good reason. Here is a link that discusses shutter shock on the Z7:
https://blog.kasson.com/nikon-z6-7/shutter-shock-and-the-nikon-z7/