Is it possible to create/edit equations in writer in CODE (I am using the development edition installed via a debian package)? The option doesn’t seem to be present.
Not yet, I’m afraid. Perhaps sometimes in the future this feature will get added.
For the sake of updating this old thread:
Math inline formula editing is now available in Writer in CODE, so initially it is experimental from 22.05.9, see release notes.
Note: Currently in CODE it is experimental and it is necessary to change your view to Tabbed View (View > use Tabbed view) to see the option.
There is a more complete thread on Math in this forum: Support Math in Collaboraoffice