I experienced some of the same symptoms on my 2016 Nismo which were eventually traced to a defective ABS / Traction Control module (computer). This was an intermittent problem which dealer initially diagnosed as a battery problem due to the low voltage diagnosis codes on multiple modules. Further details are described in my earlier post; but I think the most important bit is that you have some electrical fault which is affecting the CAN bus creating all of the other symptoms you are reporting. The "CAN bus" is essentially the network which all of the various modules with computers use to communicate with each other.
Dealers troubleshoot vehicles strictly by following the diagnostic system codes and replacing whatever it tells them is reporting the fault. This usually works, but when the problem is on the CAN bus itself, they quickly get lost; and therefore they would rather just give up rather than do the real work to figure it out. My dealer was able to figure it out my intermittent problem only because I as able to drive it to them and leave it running when the symptoms were present, they used the approach of unplugging various modules connected to the CAN bus until they symptoms cleared.
You are in a very difficult position with an uncooperative service dept and need to get Nissan's help to apply pressure to the dealer or to refer you to a more competent one that can help you. Having complete written records of everything that has been done with all of the reported trouble codes is essential so you are certainly on the right track. If you do not get the help you need from Nissan, do not give up and keep asking for your case to be escalated until you get real help.
Finally, remember that your dealer's Service Dept manager has a boss which is probably the General Manager, and I would go in and ask for a face to face meeting with him. You should ask him why his Service Dept lacks competence to correctly diagnose and repair your car, and do not accept surface level answers. You can use this info to get Nissan's intervention; so take meticulous notes or even record the conversation on your phone to help you.
Good luck and here's the
link to my previous post