You just need to find a smaller walled garden that can be tended, and not care deeply about having a massive audience and you can still find interesting conversation.

I've seen many Lemmy communities die because their creators abandoned then when they didn't grow fast into thousands of members. This fast growth fixation is so pernicious, if anything web forums and Reddit showed us, is that small communities are higher quality than big ones. Communities in the thousands require a lot of moderation effort to remain high quality.

Enjoy your small circle of internet strangers sharing a common interest, you don't need to become viral.

The gardens that need the most tending, and that will have the most impactful rewards for individuals and communities as a result of said tending, exist in meatspace. Stop searching for walled gardens on the internet and focus on whatever is around you wherever you are. Stop using "More social media but different this time!" as the solution to broken social media.