I’m also not sure how this would work from a technical perspective. Would community creators have to share their Matrix credentials with their Lemmy instance/client? Would the Matrix room be created by a different Matrix account managed by the Lemmy instance maintainer? How would it work if the Lemmy community creator wanted to use a different Matrix homeserver than matrix.org? What if a space was better suited for Matrix than a room? How would the community maintainer change the room in the future? What if the maintainer for a community switches and the new maintainer doesn’t have access to the account that is running the Matrix room?

I’m not sure if this is already available, but I think a field to enter a Matrix room/space link would be better than the ability to automatically create a Matrix room. It would give the community creator more flexibility and creating a room/space doesn’t take too much time. If a person is going out of their way to create/maintain a Lemmy community, they should also have the ability (or the ability to figure out how) to create a Matrix room/space.