A few ideas for you guys:
1. Apple already supports iMessage for Business which is intended to cover the use cases you are targeting. But the set up process is ridiculous (for example: https://help.webexconnect.io/docs/wxcc-apple-messages-for-bu...). It would be amazing to have "Vercel/Resend for iMessage for Business"
2. If you go the send blue route, please support iMessage app payloads. Send blue doesn't support that
I understand how examples like this stick in people's minds, however, just because one company decided not to move forward with a technology doesn't mean that all companies will do the same.
Facebook has continued to use it, Microsoft has begun using it heavily, Twitter uses it on the web[0], Discord has been very happy with it -- and countless other examples.