I've seen a similar example in the yoga Down Dog app, but in this case mobile is the main app an web is ancillary. On mobile you can pay the subscription, or they tell you to register through their website if you want to save 30%. So basically they charge the app store tax to the users who choose to pay through the mobile app.

In your case, maybe as you mentioned just redirecting your users to your website? Unless your marketing strategy relies strongly on users first finding you through the app store. In that case, not being able to experience what your app does before creating an account will cause drop off - I would give some kind of free roaming around until they need to sign up, similar to what Down Dog does.

All said, no idea about if that is actually allowed in the stores ToS / not enforced, but as you said, it seems that large apps do it, but also smaller ones.

Unless you are a name brand already pay the tax and focus on growing your user base. Any additional friction (even a paid app up front in most cases) is going to stifle your funnel.

Make a mobile web site?

This isn’t a mainstream solution acceptable to most users. I didn’t create this environment. I’m just attempting to optimize within it.

Most people don't use mobile web sites? Really?

That’s not at all what I said.

A mobile website is not an acceptable ‘form factor’ for functionality one might expect to find in a native app. It violates user expectations and is a significantly inferior medium for achieving mobile clientside functionality because it introduces friction and there are limitations on what can be developed (e.g. no notifications).