How so? Offer to install the pwa and unlock functionality only after the user has paid. How is that different from a paid "app"?
Everything is doable, and I recognize that my comment of “doesn’t work” was exaggerated.
But I don’t think small apps will do all that work when it is easier to monetize with ads. A more likely scenario for ad-free utilities will be having umbrella subscriptions a la Netflix (like Apple Arcade).
I’m a web dev, too, and I read many enthusiastic articles about PWAs as the future. (Mostly from Google evangelism, for a good business reason). But, the “old school” guy in me that grown-up loading games in diskettes feels that something is lost and more invasive in that future. (I’m not comparing it with the current App Store experience but with the experience of macOS/Windows/Linux, where you can still manually install app binaries).