Hi, Well...It depends. Take this with a grain of salt as I'm not a mobile app developer. I would weigh in some factors. If I would want to go fast, maybe I would make an Android app and use the language that I know, Java or even Kotlin. It really depends on how much time do you have. Alternatives to Flutter you can find here: https://buildfire.com/programming-languages-for-mobile-app-development/. As you already went with Firebase it might be a good option to stick with Flutter as they are both Google products and their integration might work more smoothly. I would also take into account the job market in your area and your personal preference in order to raise your chances to find a good job after you graduate and use your project as actual work experience. I guess it would help to put in some specs related to what you are trying to build, as some frameworks are better suited to do one job, rather than others and hopefully get more specific answers.
