Yeah, if that had been the case, I wouldn’t be asking the question. It’s not the same thing. The DMARC reports don’t show the “from” address. They show the IP addresses, and none of the IPs in the reports resolve back to anything obviously related to Shopify. I’m assuming Shopify either has space on another company’s servers or uses another email service, or something like that.
I’m not certain, but based on the size of the company, process of elimination, and a bit of Googling, I’m guessing that the Twilio Sendgrid listings I see are the ones send by Shopify. Would have been nice to have someone provide that info, though, so I know which sources are working and which aren’t.
Hopefully this is helpful for someone else out there.