Yes. I made the mistake of setting up Google Home with my “Google Apps for Your Domain” account I used since around 2009. Now I’m married and can’t add my wife. It’s been years and no changes: it still doesn’t work.
Welcome to the future :)
So we effectively have a custom domain in gmail, for sending and receiving.
As far as the internet is concerned we are one entity with multiple devices.
The easiest way I know to have smtp for your domain is AWS SES.