My recent experience with an old ticket here on the messages side of things.
There was an existing patch with a large change. To begin with I dug in an produced a large draft PR and opened a forum post. In doing both I was able to see a way forward with a smaller PR (that I am working on now).
Essentially what I am saying is that the way forward for an MVP might reveal itself through the larger PR.
The other realization I had with the above ticket is that the first changes that need to be made are ones that enable the feature to exist in a third-party package. To put this in context, of emails, How would I send a templated email using the existing Django API (send_mail etc)? This is probably a good starting point