I have not seen anything in the documentation suggesting SwiftUI 2 supports setting the first responder unfortunately.

I highly recommend Paul Hudson's intro programs at Hacking with Swift. He has a 100 Days of SwiftUI course, which would be an excellent place to start. It will walk you through learning Swift in the beginning then start building apps with SwiftUI. There's a ton of free content on his website ranging from beginner to advanced. Additionally, John Sundell writes excellent content on his website Swift by Sundell. He has a basics section, which would complement the 100 Days of SwiftUI quite well. He also covers advanced topics and everything in between.