I’d consider it 3-4K in additional value to me, as I’d put one in down the road.

I personally would like it on there. Even if you don’t track, it’s an option that comes from the factory (but not in the USA) and belongs on this car.

Highly unlikely that a US dealer can Certify a vehicle with a role bar installed

My 997.2 GT3 was sold certified with a roll bar.
I also purchased a 2010 GT3 RS CPO with a roll bar in the past.
maybe things have changed.

Removing the cage to CPO the car is a pain but then having to buy new carpet pieces to replace those that were cut to fit the cage makes it worse. High probability that the same steps will be repeated with the next owner!

Exactly same for me. The best way to go. Dealers will CPO a car with a roll bar. What my Porsche tech told me with regard to the CPO and aftermarket accessories is this: if the part interferes with systems/parts under the warranty it can be certified with specific exclusions. The roll bar does not interfere with any such system and thus can be considered for CPO without any exclusion. If the car has stuff like aftermarket exhaust or brakes or suspension parts it can technically still be certified in the US with written exclusions. It would seem PCNA is much more lenient with warranties on our cars than seen in other countries.

My particular RS had a roll bar, harnesses, sub bar, AP rotors, pads, and Akra race exhaust. The brakes and exhaust were removed and returned to stock so the car would be certified without exclusions on those systems. The parts were in the sale and subsequently installed after the fact.

In short - dealers can absolutely certify cars with roll bars and other parts installed. Whether they choose to or not is their discretion.