Substack might not be a bad bet to try to find readers/buyers.
I have no idea if my 'strategy' makes sense, but I have just been hanging around on the platform, linking up with a few folk from medium, 'chatting' to others, cross-posting the odd story.
In 2 weeks I have 16 (non-paying) subscribers, which according to my stats here took 6 months on Medium.
The question is what value they have - do they actually read what you write, and would they pay for it.
Since a paid sub is $5/month (god knows why people pay that, since even famous names post a bunch of their stuff for free), a one-off $4-5 for an ebook seems like a good deal. I've seen people asking others to send them links to their ebooks, as they want to discover new stuff. Again - do they actually follow through on that?
But it seems fairly easy to discover people with moderately aligned interests, and there is plenty of talk, at least, of 'writers supporting writers'.
I feel it's worth trying it out for a few months, though I hate having to start all over again from scratch building a 'community'.
If this place worked properly, I'd be perfectly happy.