How are you supposed to subscribe to Apple One (or manage a subscription) from your Mac or the internet?
The FAQ on the Apple One signup page at https://www.apple.com/apple-one/ indicates that signing up (or managing) from a Mac is possible, at least if you're running Big Sur.
Don't tell me no one at Apple, Inc has a computer any more and thus didn't test this.
MacBook Pro 15″, macOS 11.0
