That legislation would affect things for a service like ProtonMail, but although it’s ill-conceived doesn’t affect Fastmail: https://fastmail.blog/2018/12/21/advocating-for-privacy-aabi...

It’s just as private as Gmail, which is the comparison in question.

If you want secure, you wouldn’t be using email in the first place.

Gmail is under US jurisdiction though which provides far more protections depending on circumstance.

I wouldn't consider them equivalent. Australian laws are some of the most intrusive on the planet and are shared amongst the 5/14 eyes without a warrant.