Do there exist open data online sites where one can submit nematode micrographs, VCE videos, and image metadata? A content management system like Drupal could work. The level of effort and maintenance of such a site would be high.

Extending NemSyst (https://nemys.ugent.be/) with a citizen science add-on that allows users to submit observations?

Many of the existing sites are not quite there yet as far as nematodes go. iNaturalist.org is close -- https://www.inaturalist.org/. May be able to make it work?