Just this week I've had an app stay for 9 days in review and another one for 8 hours. Same dev account, same niche.
Yes, for a while they were doing very well and I even once had an app reviewed in <1hr but the average has been creeping up. LLM/Vibe coding is what is often blamed for this increase though at the end of the day it's Apple's problem/fault for not staffing the review department better.
I just ran an analysis of my apps and the fastest was 8hrs (June 20th) but since then it's been trending upwards with my last 3 updates coming in at 40hrs, 67hrs, and 98hrs. These are all my apps, the company I work for has at least 2 recent updates that took over a week. That's just absurd.
If the App Store can commit to 24hrs being the max time then maybe I'd be interested but for the foreseeable future I'll "Settle" for instant updates when I have a fix ready instead of waiting on Apple. Especially with how random approvals are (not just the time, the approval itself), I'll ship a tiny fix and App Review will kick it back for some native API I've been using since version 1 that they now want more info about. I don't fancy having my businesses at the whim of Apple Review.
KMP can be seen as a token optimization at this point. Business logic is shared and doesn't have to be rewritten in Swift.