2018 Nissan Versa Plus SL, just over 75,000 miles

I haven’t had it scanned recently but last time my mechanic buddy did he said it wasn’t giving any codes.

It’s an automatic CVT transmission which i’ve heard Scotty talk a lot about (almost nothing good). It started out fine when I bought it but quickly deteriorated as I started driving it more often. At night it’s slightly smooth but during the daytime (10am - 6pm in the Florida Panhandle) I think I could have a more comfortable ride on a budget go kart. It makes weird noises trying to shift, the car vibrates and has little jumps, and overall I slow down traffic trying to drive this thing. Not to mention there is a chasing bearing sound now which is only getting more unbearable and embarrassing on the road. I’ve had it looked at by a mechanic who said it “might need to be rebuilt” (I don’t think he ever actually checked it, just drove it) and suggested they do a transmission flush. This did almost nothing as far as I could tell. Still had all the same problems except it was a bit smoother at idle. I got a letter from Nissan saying they will replace my transmission up to 90,000 miles—but they want $180 just to inspect the transmission alone and will only replace it if they deem it is the transmission causing the problems. Anything I can do to help my transmission without the dealership dilemma? If I do take it to Nissan, what are the odds of them finding it’s the transmission that is the problem? Thanks and well wishes.