Neither on emacs and nor it’s a Mac first app. Probably the most misleading app name ever.

It isn't compatible with TeX/LaTeX but it does serve the same purpose (and converters are available). I don't disagree it's a weak name, though. The naming implies some sort of rich LaTeX editor plugin for emacs - I need Mike Meyers to leap out and say "Texmacs is neither LaTeX nor Emacs - discuss."

It’s heavily inspired by both TeX and Emacs, hence why it’s named after both of those. As if the author had added the best aspects of the two and then some.