As stupid and simple as it sounds, but I recently tease a bit the upcoming launch of my app on the relevant subreddit (quite a niche tho, with "only" 45k members)
I just posted without any expectations, but receive a lot of feedback and encouragement or love from people.
So, I would say, do not miss this little part of marketing. All that took me was posting a screenshot and a good title. And do not forget to reply to your early feedback!
Was in the top 24h posts of the subreddits then.
(here it i if you are curious: https://www.reddit.com/r/macapps/comments/vrjada/any_f1_fans_here_a_formula_1_calendar_right_in/)