I’d like to highlight your comment at the end: if you make a Portable Web App (PWA), it’ll run on iOS and Android and doesn’t require a developer subscription, an App Store or anything else. Just knowledge of the APIs and an idea.

Once you’ve proven the concept as a PWA, you may want to convert it to an app to get access to more protected APIs and get it onto the official App Stores though.

But with WebASM as a target, anything that doesn’t require a specific OS API runs just as well through a PWA as using an official dev environment.