As long as they are the active release for about six months, yes, but it is up to the branch managers to decide what to merge at that point.
6.2 will be an exception, as a new longer-term bootstrap branch, but that upcoming process has not been laid out yet.
Completely up to you, if it helps you in some way, say to create an Alpine package of Swift. Since Swift 6.4 releases in the next month or two, it all depends if you plan to release that for Alpine also, and if merging the patches upstream helps you with that in some way.