If you're able to target upcoming iOS15 I'd say go for it, I think a lot of people will jump on in this years iteration. I've been working with it since it's announcement and am now on a team building multiple products around it. If you need to build a complex macOS app I'd say stay far away for now but for iOS it's shaping up really well. Expect to use UIKit for some of your UI.

Absolutely YES. You can try out Kwayet and see for yourself.