Pre 2020-.2, Create supported both GET and POST with Generic APIs (but it was a well kept secret), try it with POSTMAN or similar to check it out. With 2020.2, the full range of verbs is supported (again just wiith Generic APIs - and you can select then in the build studio so have different responses for different functions).
My personal preference with non Create-to-Create APIs is to use Generic ones so you don’t have the “payload” envelope - but the down side is setting up the packets in JSON or XML yourself - and probably having to use templates.
However if you do use Create APIs, then a POST is required - as the function comes over as part of the payload.