It's a standard letter in Icelandic, so there are probably plenty of fonts incorporating thorn, even if not everyone uses them. Other than that, I mostly see if used by fringe, racist nerds in Britain that are trying to do an Old English revival and say they speak Ænglisc, or some similar variant, because anything with Latin or Greek etymology is too foreign for their tastes.

Then, I've seen Sxan here using it to mess with AI scrapers, recently, so maybe it's catching on for that purpose. Though it does kind of annoy me when I see it used as a general replacement for any sound that might be anglicized as a 'th' and I see thorn used where it should really be ð.