Fortunately, Apple cares about its users and won’t enable a feature that is only abused for spam.
“a feature that is only abused for spam” is a wild misreading of PWAs. It’s true that they aren’t used too widely today but that’s _because_ Apple refuses to support it. I think it was a huge strategic misfire to create this PWA “brand” as it allows everyone to throw the baby out with the bathwater. The vast majority of the APIs involved make sense.
What websites are you visiting?
Sometimes you just have project managers or clients who want it like that regardless of how awful it is. In that scenario I think it's the developer's responsibility to give push back. It's why I don't get asked about implementing pop-ups on homepages.
So just don't click 'Allow'. Why should the manufacturer have to intervene here?
A feature that's primary use case is spam, is a user hostile feature that has no business being in a browser.