Every engineer who knows their tools well is a good engineer. A person that doesn’t know their tools well is very unlikely to be a good engineer.
Google defined three main qualifications for PWAs: they must be Reliable, Fast, and Engaging.
…'s still possible to deal with Objective-C legacy code, but Swift has reached high maturity levels. So, if you're planning to learn how to natively develop for iOS, Swift is definitely where you should start.