It's possible to sell a PWA like sell a $5 app on the App Store/Play Store? The author doesn't address this topic and it's important to make a transition imho.
Well, since the trend goes towards In-App-Purchaes, you could simply paywall some functionality and slap Stripe or PayPal on your website. That should give users a relatively similar experience. Don't even have to share 30% that way. It's up to you.