The studder isn't good, but it may or may not even be CVT related. An advanced scan tool will show a judder code if the transmission is suspect. It's a nissan specific CVT code.
My bets are on the CVT fluid never having been touched and I guarantee it's nasty looking. This doesn't necessarily mean death of the unit, but if you are feeling "judder", it's probably toast.
The other major issue is your 2017 was probably a lease return or ex-rental at some point? If so, at that mileage the engine could have the severe sludge build up problem you will see in many posts on this site due to extending the oil change intervals too long. That can also lead to the problem you are experiencing. It may not be CVT related at all.
Keep us posted! Very wise to have some type of extended warranty, although I've read of them denying engine coverage if they discover sludge. They've been known to refuse coverage due to "lack of maintenance" even though you didn't own the vehicle at the time.