On the other hand, you do get the full (La)TeX ecosystem to draw on. If I want to draw a commutative diagram, I can add tikzcd to the preamble, and insert inline TeX to do so.

There is some support for the LaTeX ecosystem from within TeXmacs. If you want a TikZ drawing, you can insert it programmatically into a TeXmacs document in a seamless way---if you have the same font for your TeXmacs document and for LaTeX it will be nicely integrated as far as I know, You can see the blog post https://texmacs.github.io/notes/docs/embedding-tikz-figures-...