I feel like this needs a big asterisk. Can you ship a a non-trivial iOS or Mac app that uses SwiftUI or other first-party APIs without Xcode? Is it practical? Those are real questions, some cursory searching did not turn up a concrete answer.

Define "without Xcode", but if you mean "without using the IDE", yes, absolutely.

You obviously still need to use signing pipeline etc, but that can all be done via CLI.

As for "non-trivial", here are Chrome's build instructions for macOS: https://chromium.googlesource.com/chromium/src/+/HEAD/docs/m...

Which contains the words "While using Xcode is unsupported" :)

It is possible and practical in lots of cases. And it's necessary to use the CLI tools directly in some situations, such as when deploying from CI servers rather than building by hand.

Is it possible for 100% of situations? I don't know, because I haven't tried 100% of the situations. And in one case I haven't figured out yet (AUv3).