Finally gave up googling and decided to ask people with real experience.
The free tiers on most of what I've tried are basically useless — you get just enough to see real people are there, then hit a wall the moment you try to message anyone.
I've tried a few different things already with mixed results. Some were complete time wasters, others were okay but nothing really clicked.
If you've got experience with any platforms or approaches that work, drop them below.