> 2. It asks for access to your email via Apple's Mail app which I don't use
Assumption that people use Apple services by default is wild
The mail app is a native Mac app but it can use any email account. It's an SMTP/IMAP/POP client.
They probably built it just for themselves. More the first person in the post title.
Mail isn't documented as a requirement, but the first item in the Requirements section is "macOS (uses launchd for scheduling and Messages for iMessage)".