Apparently I'm not alone wanting it. I have little idea of the market potential but I believe there is some.
Apparently there are at least some investors and makers who believe the same. For example this is how they market Matic[1] (a cloud-free smart vacuum robot). Which I'm probably going to buy (unless I discover it's not bullshit-free enough) although it's expensive. I still have no robot vacuum just because every not-horribly-dumb model depends on a cloud (even though they don't have to - some are possible to uncloud but I have no time for this).
The same applies to social networks etc - they try to reach every person in the world by offering free service at a cost of the user being made a product. Let me pay money but respect me as a customer, not a zombie.
I just got a Shark XL vacuum which mostly works without its app and cloud, you just push its Clean button and it goes off and comes back to dock when it's done. But if you want schedule and mapping, you're stuck. There is a Home Assistant integration for it, but that just talks to their cloud (not well). Interestingly, that cloud saas is shared among a number of vacuum makers so it's not open, but it there's always hoping.