Re: Australia: be aware that all normal bank to bank transfers are still min 1 working day transfer. Its FAST and Osko which bypass that with their own new network (up to $1000).
Not every bank is with Osko or FAST, and some are with one and not the other. Though I think FAST is fading away with Osko being dominant.
Re: phone number: or email address! It’s great, especially if you have your own domain name. You can make different PayID email addresses for each account you have if you want.