Please post such questions in "Q&A" section.
Could you elaborate what exactly you mean with the help of a drawing may be?
In the meantime based on the understanding so far, it is not possible to have the category and subcategories within the standard view positions of menu views and primary views.
You could however take a look at and evaluate the following sample app, for the hierarchical views implementation. The hierarchy of views is not implemented using menu and primary views positions but on the mobile main screen itself.
Hierarchical Menu - AppSheet
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