2017 Engine Sludge= New Engine?

I have a 2017 QX60 Base AWD, so far 96k miles, bought it new paid an extra $4k for extended warranty until 120k miles. In the past 4 years, I have replaced the Battery (Optima Yellow top), Rotors/Brake (R1 concepts slotted w/ 30% off and EBC brake pads) and tires (Michelin Latitude Tour). Dealer fixed a recall with the ABS pump, got a free brake fluid flush. They also replaced front 2 shocks, and a coupling in the drivetrain under warranty. I replaced the 2 front lower control arms, rear shocks and sway bar bushing because the car didn’t take bumps well and was getting sloppy. Also did CVT oil change and AWD transfer-case gear oil change for $650 from Dealer to maintain warranty. Now I did a bunch of research on this carbon build up on the intake valves due to the 2017 and up QX60/Pathfinder models being direct injected. No seafoam or spray product will fix it. What you need is to do ‘walnut blasting’, the process requires removal of the whole intake manifold and hooking up a hose to blast walnut shells to manually remove carbon build up on the intake valves, It’s a 3+hours job. Also at the same time install an Air/oil separator or catch can so that the PCV doesn’t put oil in your intake that later cakes up on the intake valves. If you check BMW/Audi forums there’s people offering to do walnut blasting for $250-$300 but a reputable shop will charge around $500 and dealers $1,400. Also the 2nd row passenger seat mechanism broke making the seat wobbly, dealer said it’s not covered and wanted $2k, I declined and got one from the junkyard for $250. Also did u guys notice on the Pathfinder 2nd row passenger door panel, there is a cup holder at the top, but for QX60 2rd row door panel they deleted the cup holder at the top. Idk if anyone has swapped over a door panel from a pathfinder to qx60, cup holder at the top of the door panel would be convenient.