Time for a summary. Thanks for all suggestions and tips.
We stayed in Seiano, a bit outside Sorrento, so we ate most meals around there. The hotel had a restaurant in the complex that we ate at four times, and after all's said and ate, I think they make really good pizza. It's called Sapori. I don't know how fast they baked, but I'd guess something under 3 minutes. The pies had a nice, soft and airy crust with great ingredients. I mostly had margheritas, with and without buffalo cheese, where I preferred them with. The tomatoes were maybe not as good as in Naples, but definitely very tasty. I really recommend this place if you are looking for a good pizza in Sorrento or Seiano.
We only had one day in Naples, unfortunately. Wish it'd been more, but with just one week and not having other things to do in Naples than eat pizza, that's what I got.
We first went to 50 Kalò, a bit on the outside of the town centre, but very close to a Metro station. We arrived around 30 minutes after they opened and got a table within five minutes. I had a margherita con buffalo and glass or red wine. This pie was incredible. The soft tenderness, the flavors. Amazing. My favorite sauce of the trip.
Second visit was da Michele. After wondering how the takeaway queue worked, I just walked up to the door and asked "takeaway" and was let in. 15-20 minutes later of watching them pump out pies, I got mine and went out to eat it on a bench. Also a really good pie with great taste. I did prefer 50 Kalò, maybe because I ate it at a table with knife and fork. Being takeaway, the crust might have fallen a bit, but the pie was great. If you got the time to wait, eat inside.
We also had some ice cream at somewhere I saw someone recommend. Great stuff.
I wish I could've said we also tried Sorbillo, which I had planned for last, but because of some unfortunate events that I won't elaborate on, we had to cancel that visit. It was the placed I was most looking forward to after 50 Kalò, so I was quite disappointed. Still, the pies I had were incredible and there's no doubt Neapolitan will be my future goal at home (whenever we buy a house where I can have an outside oven). It was a big bonus that the restaurant in Seiano had such great pies, so I'm pretty happy with the trip. I had one day without pizza in one week, and wish I could've had it that day too.

I did wonder during my visit, how the pies would've tasted with sourdough. I make only sourdough now and love the flavors it gives. A proper Neapolitan with sourdough is something I'm looking forward to, but I assume I'll have to make it myself first.
What struck me most on my trip was the flavor of the tomatoes. They were absolutely incredible and I'm going to miss them a lot. I really hope to find even better tomatoes than the ones I'm using these days.
Naples as a city is not something I have a great need to return to, but I could see myself taking a 2-3 days trip sometime and eat more pizza.
On the day of our return, I was craving one more pie, so I dropped my GF off at the airport (despite her dislike with my plan) and drove back 20 minutes to eat at Salvo Pizzaioli. If I had more time, I'd gone to Sorbillo or something but it would have taken too long getting into Naples. I had a Margherita Vusevius. It was good, but the tomatoes were noticeably less tasteful than the others.
In ranking the placed we tried, I'd go: 50 Kalò, da Michele, Sapori, Salvo.