One option could be a traditional project but that would require people to know of that project’s existence, and add their observations to it. Once they are identified they’ll show up in the collection project.
A similar situation is with galls and leafminers, so there are projects (some examples linked here) that you can add your observations of them to and then identifiers who know how to idenitify galls/leafminers look through just the observations in those projects.
Most of the lichen projects are traditional projects, yet have complicated taxa requirements (e.g. here) so you have to know to identify your observation as Lecanoromycetes (whether or not that’s accurate) before you can add it to the project. I haven’t noticed receiving any more identifications after adding observations to those projects though.
Moths are simpler to deal with because you can just exclude Papilionoidea from Lepidoptera and all you have left are moths.
There are a couple suggestions for projects to use for seaweed here but perhaps a dedicated project would be useful.