There's a huge difference between the EU vs Microsoft antitrust investigations involving Internet Explorer. This was at a time when Microsoft was still the dominant player in the market and IE had a stranglehold on the browser market.

By contrast, Apple doesn't have a monopoly on the mobile device market, the browser market is dominated by Google's Chrome, and the majority share of browsers use Chrome's Blink engine.

'PWA' is a Google-invented term to describe technologies already implemented in their own browser; none of it constitutes a single standard unto itself. Apple not fully implementing Google's standard, made not for the benefit of the open web but to make ChromeOS a little more functional than a glorified web browser, is only a threat to those who've forgotten that coding for one browser is what got us stuck in the code-only-for-IE mindset and halted progress for browsers for about a decade.

Apple isn't the biggest threat to the free and open web. Google is. Everybody's using Google's browser, based around Google's own standards designed to force people to stay using Google, to access Google's search which displays Google's ads above Google's curated AMP results.