You may want to check out this thread: https://forum.inaturalist.org/t/inaturalist-data-on-gbif-shows-only-cc-by-nc-excluding-cc0-and-cc-by/9952/
it includes some discussion from GBIF and iNat staff.
CC-BY-ND observations are not exported to GBIF to my knowledge, so that wouldn’t be an issue.
I’ve seen people post comma separated lists of usernames as acknowledgements in Supp and that seems reasonable to me for attribution.