I don't know how you feel about second hand robots, but they are dumb enough to respect your privacy. The old Irobot roombas, They just run off of a internal clock, no connection to the internet, they bump around a bit, then dock themselves when the battery starts to get low. I pick them up at flea markets for 20 bucks, usually need to replace the battery, brushes, but they sell all that. Be weary if they smell like poop.
I feel that the "dumb" robots are much worse than the lidar robots. Mine
cleans very efficiently and also navigates when things move (like chairs).
A buddy of mine has a "dumb" robot and has since stopped using it because he has
had to rescue it often
Oh, don't I know it. I always find "Mildred" stuck on this stupid mini step the previous owner made, or stuck under the side table. That being said, this place would get nasty if she wasn't running 3 times a week. But those little robots have limitations.