What to build: App or Web?

Can build cross platform apps via react native or flutter for quick progress but you would still require someone with good expertise around this. Also with the app comes its own issues. You can't deploy multiple times a day as you would require app/play store releases that might slow down your deliverables.

You can tryout web + app both initially by using a webview inside your app, so users can access both but eventually down the road you will face some blockers around performance and other native functionalities.

If the solution is for engagement, with users expected to use it frequently (daily or weekly), app makes sense. Anything that is one off or low freq transactions, website is more sensible till your retention becomes high(on a high base). 2 cents.

Web to gauge traction. Mobile has superior retention anyday and you have more control.

I'd need more info to decide bt considering GenZ, mobile app would be recommended as users will be on the phone more than laptop/pc.

If it's an interesting idea and you decide to build an iOS app, let me know. Ready to join in any capacity possible.

I would say go for the web version as from a customers point of view there is always some resistance when it comes to downloading an app from Play Store. Maybe you can create a PWA as well

Depends upon your product.

Correct me if I’m wrong but wouldn’t that depend on the idea itself?

App. People use apps a lot more than Webapps. If your target is casual and not some work related stuff, then go with the app first.

Depending on your product, the fastest option would be to build a decoupled web app with a mobile friendly UI. Either build on react native or similar platform with cross platform support for web and mobile. Or, build a web app if you(r team is/ are) more familiar with the web technologies. Then later simply pack the web app frontend in a hybrid app using xamarin, phonegap (cordova) or similar.