Overall, I think it's a practical idea with a clear audience. If you keep improving the product and make the setup effortless, I can see plenty of founders choosing this over building separate mobile apps from scratch.
Your biggest advantage is simplicity. Many founders don't need a complex native app—they just need a professional mobile presence that works reliably and doesn't require constant maintenance.
If I were considering your product, I'd also want to know how quickly bug fixes and platform updates are released when Apple or Google changes their requirements.
I think you're solving a real problem that many solo founders run into. Building and maintaining a web app, an iOS app, and an Android app is a huge commitment. If your solution removes that complexity while still delivering a good user experience, I think there will definitely be interest.