I have used the AirPods Pro AND the Studio Buds extensively. All the initial reviews say the Fit Pro is now back at the level of performance of the ANC and Transparency modes on the AirPod Pro so I think I can provide some initial input, although I'll have the Fit Pro tomorrow for a final test.
AirPods Pro had what I'd consider very good ANC for an ear bud. I use the professional Bose A20 over the ear headphones that are world class for ANC when working as an airline pilot so no, it isn't that good, but for a tiny bud they were great. The transparency mode was also SHOCKINGLY good making the world outside enter your sealed ear and eerily creating the effect you weren't wearing buds.
Studio Buds ANC was considerably worse. It worked ok, and certainly took a lot of the outside noise (like airplane background noise) away and made it easy to hear your music or podcast, but the background noise was still always noticeable in the background. I'd say Studio Buds ANC is 75% as good as AirPods Pro. The Studio Buds transparency mode is HORRIBLY bad. It barely lets the outside world in, you sound weird to yourself when talking, and it never sounds "real" but rather you have noise being pumped into the earbuds (which you are, but AirPods Pro proved it doesn't need to feel that way.) I consider the transparency mode on the Studio Buds unusable for carrying on conversations or listening to the outside world, it has some usefulness for safety on runs (hearing a car approaching) but even then it is so weak that I don't feel it is good enough.
Fit Pro reviews are saying the ANC is the equal OR better (likely due to secure fit, more than improved tech) than AirPods Pro. This is great news. The reviews are also saying the transparency mode is the same as AirPods Pro which means it should be light years better than the Studio Buds.
The Studio Buds proved to me that the small bud design works better for me than stems, the sound could still be good etc. But adding the wings for better fit and restoring all the ANC/transparency/Apple ecosystem tech will be a HUGE upgrade from the Studio Buds and so the Fit Pro seems on paper to be the perfect headphones for me. I'll give you first hand impressions tomorrow hopefully.