After a bit of experimentation and tinkering tonight, it appears that one can use their website to create threaded conversations on (and likely other portions of the ) using the IndieWeb syndication strategy of POSSE with backfeed of comments using and Brid.gy. I’d outlined the process using Twitter in the past, and the same principles seem to work well for Mastodon.
Perhaps hidden/unknown to many, but hcommons.social and other instances running the Hometown version of Mastodon, have the ability to post only to their local community and specifically not federate their content to the broader Fediverse. In the posting interface, click on the link icon and choose whether you want to allow your post greater reach or stay only within your community. This can be a helpful affordance for having smaller/restricted conversations.

User interface from hcommons.social highlighting the fifth icon, a link, with a drop down menu to choose either federating one's post or making it local only.