Hello @PetK,
Submissions format depend on the editing guidelines. Usually, either .docx documents or .tex are accepted. If you do not see the Typst format being outright rejected, then I’d suggest to ask.
For publications such as theses, it should be relatively easy to get it accepted, see Paris-Saclay PhD thesis template (they probably don’t even ask for the source).
You can also read the thread at Which scientific journals are accepting Typst files as article submission at current date?.
For a more detailed answer, most journal use specialised tooling (eg Open Journal System, Elsevier EM, etc.) to manage submissions. If the Typst community wants to increase their chances of getting a Typst source document accepted, then we should target these support platforms for adoption first.
tl;dr: adoption is zero, because Typst is unknown. However, if you ask, you might have a chance at getting your submission in.