I could find this useful with some types of transactional emails. I'm currently working on an app where a user submits their timesheet and an email is sent to a manager to approve the time. Right now the manager has to click "Review Time" in the email where they will then be kicked out to a portal I setup that lets them review the entries. With something like AMP I could embed all that logic in the actual email, letting the manager submit a review without having to leave that email.
The problem with all of this is none of it will work because of platform support. Like you said support for AMP Emails is limited to Gmail and maybe a handful of other clients. Part of me wishes that AMP Emails were an actual standard rather than a "standard" that google created to help itself. And with only Gmail really having support, you know this will only ever get used in marketing shenanigans and to more deeply track you.
The problem with all of this is none of it will work because of platform support. Like you said support for AMP Emails is limited to Gmail and maybe a handful of other clients. Part of me wishes that AMP Emails were an actual standard rather than a "standard" that google created to help itself. And with only Gmail really having support, you know this will only ever get used in marketing shenanigans and to more deeply track you.