i was thinking about this again, and actually, the last part is not true. so this method could provide (near-)real-time data for up to 200 observations at a time. for example, here’s a quick example in AGOL where you can click on the points to see observations details in a pop-up. (it refreshes data automatically every couple of minutes.)
otherwise, if you just want to see the data on a map, without getting the underlying observation details, it’s still possible to use the XYZ tiles provided by the iNat API to do (near-)real-time visualization of unlimited numbers of observations.