App for people to surrender knives in locally based bins

Hi. I've been asked by the charity I work for to create an app so people can register to surrender weapons in to locally based bins placed around my town. This is just a general query as I suspect they would require the app to work on both Apple and Android devices.

I do have an outline of an idea whereby most of the work would be carried out on a google sites website via sheets and the frontend would be more or less just a link to the website.

My query revolves around the issue of compatibility with apple IOS. Would this app even be possible using app inventor or should I look elsewhere?