Suggestions for determining which species have not been previously documented (on iNat) at a particular place

look at: https://forum.inaturalist.org/t/several-external-tools-for-inat-data-by-kildor/19906.

the first item listed in the original post might work, depending on whether or not you had a corresponding project set up for the place.

or you could ty the thing that i mention in the subsequent post in that thread.

these and additional options are also discussed here: https://forum.inaturalist.org/t/how-to-search-for-1st-records-in-a-region/25114/8. moderators might actually want to consider merging this thread into that thread.