I _think_ (not entirely certain as the docs are pretty bad) that the very-recently-accounced Google Cloud Identity free tier does almost that for free; but it's

I _think_ (not entirely certain as the docs are pretty bad) that the very-recently-accounced Google Cloud Identity free tier does almost that for free; but it's just the identity service, and doesn't include any apps like GMail. Not sure if it has mail routing settings, or if that's just standard DNS.