Even if you learn SwiftUI, and get a Kotlin developer for Android, you'll still need a web developer for those who just want a web app. Notion, Spotify, Hulu, etc, all have web apps. Even Gmail still has a web app, albeit an extremely poor one, which goes to show how much work multi-platform support is. The benefit of frameworks like Ionic is to support multiple platforms without having to maintain multiple codebases. So as the gap shrinks between native and web, it starts making more sense to just write a single web app
Gmail's web app is "extremely poor"? I almost never experience any issues with it, and it's quite streamlined in my experience. It's not worse than the Android app (it's actually nicer, IMO, but that's probably in large part because it's on a big screen). It could be more responsive, but that's about it.