You're gonna have to fork one or build your own from scratch.
Primal is on both iOS and Android so I think it'd be a good one to fork.
Thanks, I appreciate the reply :)
Ideally I'm looking for something where iPhone users and Android users can meet. Since I want to set up QR codes on campus and start organizing people via actual posters
Here are more details of what I'm looking for: nostr:nevent1qqsdgavxduf3l66h740tqdhxalhqjlywk6vsuslw9u0ymrlkxkdc7cgpz3mhxue69uhhyetvv9ujumn0wd68ytnzvupzp7spvks0ryhmp6gu0kr3pet4wzkj0vm3tjjjrq0kc57fkgpnjurnqvzqqqqqqy604gcj
Discussion
Might be worth doing. I'm looking into starting a local nostr community at the Royal Institute of Science #KTH in Stockholm. There are lots of programmers here, so it might be possible to engage some fellow students in building something suitable as a community project!