If it runs on iPadOS, it must be optimized to display properly on all models of iPad Pro.  Does this mean that I can only focus on iPad Pro models? It sounds like I should make it work properly on iPad Pro if it also works on iPadOS I should've wrote this as a comment.. but there is no delete button..

If you mean the documents such as student status document, then no. This can be in any languages. Only the app you made should be in English.