I suspect there were limits to how much Russia was willing to share with China in these "strategically" sensitive areas in the past. I also suspect that China would still jump at the chance to get their hands on a Pr. 885M boat if that were even remotely possible, which it isn't for production reasons if nothing else. Yes, they leased an Akula to India, but then India in the medium-term was and remains much less plausible as either potential threat or competitor. As an aspirational target I would hope and expect that China would be aiming to at least match if not exceed the latest contemporary designs, i.e. Virginia Block III, Yasen, Astute. I don't know if that can be achieved, but I'm sure they aiming for it and I would not exclude the possibility.
The idea of China buying 885M is a bit of a counterfactual that's difficult to even talk about without being specific, but I would say that China would be interested in having a look at it but I suspect they would not be interested in buying it as an operational platform simply because whatever benefits it may have does not outweigh sustaining a massive support system for a new class of expensive, bespoke foreign nuclear submarine, given the rate of development of their own domestic programs.
The example I gave of Constellation only accommodating one hangar and lacking bow sonar was probably a little cheeky, and I freely admit I made it mostly to link to previous discussions about the ideal number of helos for ASW combatants. Certainly it is a very relevant counter-observation that most of America's surface combatants (i.e. all the Ticos and Burkes) have dual helos. That said, I think my broader point regarding USN's apparent lack of concern re: Chinese submarine capabilities stands. The rise of China has prompted major American programs aimed more-or-less directly at countering what they view as a rising threat. The B-21 Raider program is probably the most significant example of this. Entire services such as the US Marine Corps are publicly and painfully restructuring in anticipation of a "Pacific conflict". Yet American public discourse about their submarine and anti-submarine capabilities, seems to be almost entirely driven by internal considerations such as maintenance backlogs. There appears to be little concern about the adequacy of existing platforms and systems like MH-60R, P-8I, Virginia, ASROC, Mk. 48 ADCAP, undersea surveillance networks, etc. to meet actual and anticipated advancements in China's submarine capabilities.
Eh, "USN's apparent lack of concern re Chinese submarine capabilities" doesn't really stand, in fact it shouldn't have been made as a point to begin with.
1: the USN's (or US military overall's) level of concern towards current and future "PLA capability in XYZ domain" is not necessarily reflective of reality. I of course have respect for actual US intelligence services and I imagine they probably have a grasp of future PLA direction and procurement and scale, but that doesn't mean it will influence the people in charge of making procurement decisions. We have seen in multiple domains where PLA procurement and development of new capabilities have caused public alarm and surprise at their speed (surface combatants primarily being the most relevant one here), and it's not like the USN was actively retooling their entire strategic procurement decision in anticipation of that.
2: you seem to believe that the quality of PLAN submarines will determine the USN's evolution of its ASW capabilities. Chinese submarine capabilities instead should of course reflect both quality and quantity, as well as the relevant domains in which they'll operate. Chinese SSKs are already very competitive and world class, but they are unlikely to operate outside of the first island chain in any meaningful way in wartime -- in other words, in terms of ASW, the ability of the USN's ASW capabilities to target Chinese SSKs would be dependent on how the rest of the multi-domain conflict in air and sea domains in and around the first island chain goes. As for Chinese SSNs -- the PLAN has very few SSNs to begin with; it is only fairly recently that they have something like their SSNs approach and meet the two digit mark, and even then many of them until fairly recently could be considered even "somewhat competitive". Even if tomorrow the PLAN launches their first 09V and let's say it is hypothetically as capable as the best (or superior) as what the USN has, unless the PLAN can massively and rapidly scale up production and commissioning of them (say, produce 60 of them in the span of 5-6 years), the USN already has such an extensive ASW capability that they'll have enough leeway to adjust strategy and carry out procurement of its own. Heck, for something like the MH-60R (the USN's primary ASW helicopter and arguably the world's most premier and capable ASW helicopter type), the USN actually bought too many of them as assessed back in 2019 due to cutbacks in the LCS program, so it's not like they are at a deficit or stretched for platforms -- and similarly in terms of ASW MPAs the US has the largest and most capable fleet in the world as well.
That said, even the USN's next SSN(X) is oriented more for hunting other nation's submarines in deep water rather than being more "multirole" (yet still very capable of course) like the Virginias, so clearly they are recognizing there will be competition in the future (though one may argue this is just the USN wanting to keep up the scale of their advantage).
.... all of which is to say, the USN's "lack of concern" towards current and more importantly future Chinese nuclear submarine capabilities is not useful to us for actually projecting current or future Chinese nuclear submarine capabilities, and more importantly the USN's existing ASW capabilities are already so extensive, that a USN reaction to current or future China's nuclear submarine capabilities would be as much about quantity as about quality.
We are at this stage only interested in talking about the quality/technology/competitiveness of a future Chinese nuclear submarine class (09V and by extension 09VI), and the speed of its procurement and scale will be as important as how individually capable it is.
