I and three other people got some money to build an educational mobile app (sociology for high school students). The software requirements are decided largely by ourselves. The team will consist of the following people: two experts, one whose role is to create the teaching material (questions, text, etc) and one who will provide expert advice on pedagogical principles and teaching sociology; a programmer (me); and a person who will design the UX and UI.
I have previously worked on such projects in academia without a proper framework for software development, but this time I would like to do it right from the beginning and follow the best practices. Therefore I would like to ask: What kind of a development process would fit for this type of work and how do we go about choosing one? I am not sure how using scrum would work here; it's a small team and the people involved have varying commitment levels (we don't have a tight deadline). Is there any other development process type that would work here?