I self-host a metric fuck tonne of services and (with my extensive email background) I choose to outsource my email services.
You CAN do it today. But should you? Given DMARC, SPF, etc... No.
Since I left Gmail's free GAFYD feature, I moved to Fastmail (Australian) years ago. Does it cost money? Yes. Does it do everything I want? Yes. Does it have features Google would never provide? Yes.
Do I have any reservations or regrets? No.