Just use WordPress with LaTeX for now. Stay compatible with mathjax but can use any amsmath, amsfont and amssymbol.
Separate notes for enormous range of econometrics and other modeling software that can be easily integrated via SciPy (and R2py) with Sage. Thomas Sargent has python QuantEcon. His textbooks are central for studying current Macroeconomics theory.
Use Jupyter notebook either from Sage or as front end to Sage and others or use TeXmacs as front end. Jupyter should work from Android using just termux?
Use Zotero/Calibre/Library Genesis for bibliographies and collections. Compatible with non maths writing too.
Note: nLAB uses MathML (and presumably so does HTT at least on their wiki that is part of nLAB). Pandoc can translate MathML.
HTT mainly uses Coq but also Agda which has a syntax like Haskell so if learning a functional programming language to help learn HTT, go for Haskell. Scheme is also a functional programming language (and dialect of Lisp) and Guile/Scheme is the “macro” language for unleashing the full power of TeXmacs and for other GNU scripting. But better to start with Haskell while learning lambda calculus and type theory and only add Guile when actually needed. On the other hand Scheme is minimalist and widely used for teaching programming (and I have hard copy of SICP) so take a look at both – even some Python programmers like Guile.
Firefox browser has best support for MathML (and Zotero and many other things).
Eventually there may be some combination of TeXmacs and Coq that adds semantics with MathML
Meanwhile TeXmacs should be fine for exporting LaTeX snippets to WordPress and as a general purpose editor. Does not import LaTeX well. For complying with publisher style sheets may need to switch to a TeX editor. So keep LaTeX syntax visible and learn it while using TeXmacs (eg use keyboard not just menus).