With SwiftUI @State (not sure if its this apply to other PW), the auto generated nil initialization is conditional: it depends on whether there are other PW and if they are initialized. If not, no implicit initialization to nil!
So using my example:
@State private var a: Int? // Will this be already nil by init? Maybe
@Stste private var b: Optional<Int> // if this is initialized here then a above is auto nil, if not, no auto nil!
This basically sums up the whole problem that prompted me to start this thread and that other original thread.