> Try to get Google Maps or Apple Maps running on a phone with more than 200 Markers/Annotations

That the big tech version of this is pretty shit, should come as a surprise to no one. The OP's visualisation runs fine on my phone, presumably Google/Apple could do this too, if they were willing to spend a big of engineering time on it

My iOS app using MapKit is smooth with ~4k annotations on an iPhone 14. My experience is that it doesn't really start to choke until you get closer to ~10k.