Sincerely a selfhostable service to create memes using a base image you choose from like a dropdown or something, some text, and some basic positioning could be nice, with the option to add new images on the fly. I’d definitely use it, so that I don’t upload my own photos to someone’s server.

It might just be that if there’s an OpenSource option they prefer to use and support that, no need to have a threat to use something open.

Alternatively, maybe they want to create memes with their own personal images or text that they rather not upload anywhere. The reason for why they prefer some OpenSource option, maybe something to selfhost, is irrelevant to the question by OP.