The current IRS online account system with ID.me does allow signing up with foreign addresses, and then you can download transcripts there. Your struggles were

The current IRS online account system with ID.me does allow signing up with foreign addresses, and then you can download transcripts there. Your struggles were probably with the previous system, which only allowed creating an account with a US address. It did however allow placing an online request without an account for a transcript to be mailed to a foreign address. I did this successfully myself and received the mail in Canada.