Bindings might be better but that doesn't necessarily mean that ViewControllers are an anti-pattern. Is there a better way to do it in an non-declarative OOP way?
not the op but what i usually do is just write a plain-old-class with actions/outlets/delegate-methods and place those in the storyboard/xib
if you are programmatically doing it, then you can just init it directly or use some injection/indirection mechanism
you can use the responder chain to send messages up to the nearest view controller if you need to, and if you need some lifecycle awareness, you can always delegate those from the view controller in various ways (protocols, notifications etc)
testing is also easier since they are plain objects with a few methods on them (just fill in their outlets with mocks and you are ready)
And yeah it's easy to use a SwiftUI view in AppKit or UIKit using a UIHostingController or NSHostingController