I'm also a heavy Fastmail user and just wanted to recommend Harmonizely for integration with it. It's a service like Calendly that works directly with Fastmail.

I'm also a heavy Fastmail user and just wanted to recommend Harmonizely for integration with it. It's a service like Calendly that works directly with Fastmail. This is important as while you can kind of hack together a Calendly -> GCal -> Fastmail loop you still end up with every meeting have extraneous Google Meet links in it, etc.