I’ve been doing what little I can to participate in less-niche, but still off the beaten path, communities (3D printing, photography, etc). Posts in those communities will generally get a decent level of engagement, but the communities themselves don’t see a ton of posts so there aren’t that many opportunities for people to engage in the community.
Like most social platforms, the majority of users here are lurkers. Some of those lurkers will comment. Some of those commenters will create posts.
Go post content! Nurture communities! That said, true niche communities might not be realistic right now but there’s likely a more general community the content could fit in while lemmy grows.