Tech stack help

Hello,

I am developing an app for my school. I have a year and a half to complete it. I was wondering if someone can recommend me a tech stack that is cross platform and uses Java for the backend. I know Java html css and JavaScript. The app would contain videos on one page, a barcode button to scan into the weight room. Lastly, a settings page. It would keep track of the students name and time they entered the weight room(idk if this is a sql thing). The rest I’m sure I’d figure out like 2fa through our schools company, figuring out how to keep users information for them to log in, etc etc.

So if you know of any tech stacks that will be good for this project I’d appreciate it. I’ve only programmed school work until this point but I have a lot of time in my hands to make this app. It would be a great thing to add to my portfolio. Thank you.