I've just checked LyX, actually it's quite good and similar to Mathcha, but actually it serves different goals/features than Mathcha.
- LyX: full Latex compiled, and Mix between WYSIWYG and Latex Script. Mainly use to create Latex Document
- Mathcha: can export some parts to Latex (mostly Math mode) but does not guarantee to compile, a full WYSIWYG editor. The goal to just create Document without constraints to Latex format
- LyX: full Latex compiled, and Mix between WYSIWYG and Latex Script. Mainly use to create Latex Document
- Mathcha: can export some parts to Latex (mostly Math mode) but does not guarantee to compile, a full WYSIWYG editor. The goal to just create Document without constraints to Latex format