These days? Pretty easily!
Fastmail also has an email client, and a calendar. The calendar is integrated into its email service too. And the calendar integrates really well with iCal / CalDAV. I find fastmail syncs calendar entries between my apple devices more reliably than apple's own icloud.
The big hole in fastmail's offering is that they have no replacement for google docs & spreadsheets.
Microsoft Outlook + 365 (as others have suggested) also does pretty much everything gsuite does.
Since they already manage the domain for email, spinning up static sites at subdomains is really easy and really nice.
Edit: I’m pretty sure the sync options are part of the put command
I'm happy about this. Those are really complicated apps to support; they'd have to spend a ton of time and money and dedicate new teams to them (even if they "just" hosted OSS alternatives) which would raise the cost of my subscription and take away from their core competency (e-mail). And it may result in proprietary features, making it a lock-in device.