I checked out Pleroma after seeing it mentioned on that freshports mastodon page, which seemed a bit less onerous with just the OTP component but they don't distribute an i686 build, that's unfortunately what the dusty old colo I'm looking to run this on has.
As for GNU Social, well... https://wiki.debian.org/FreedomBox/Manual/GNUSocial
You might be interested in Yunohost, which is a Debian-based distro packaging popular server applications (also with an easy installer, aimed at non-technical people): https://yunohost.org/
For posterity sake:
I just spent an hour trying to get that package happily installed in a fresh debian sid debootstrap running in nspawn and it seems to be broken. They're requiring an old 1.2.x ruby-zip version, and sid seems to only have 2.0. Even after kludging past that, things break down again on unmet sass version requirements.
So true to the 'unstable' name, this package isn't currently usable.
This will more likely result in the package being removed rather than fixed, but at least someone else won't get false hope.