Have a look at TeXmacs! (https://texmacs.org https://texmacs.org) (AFAIK, you can run Mathematica sessions in TeXmacs, get proper typesetting, and can copy/pas

Have a look at TeXmacs! (https://texmacs.org https://texmacs.org) (AFAIK, you can run Mathematica sessions in TeXmacs, get proper typesetting, and can copy/paste expressions for simplification by hand or using other CAS sessions in the same TeXmacs document).