If you know of a development agency, odds are that it is probably a body shop.
The places that do work like this are more like Unicorns. And Unicorns are damned hard to find and hire -- or get hired by them.
This sort of thing is how I now pay the bills.
In many cases, what somebody does (and why) is not documented, or if it is the documentation is most likely out of date and inaccurate.
To effectively automate a task, you need to fully understand what needs to be done as well as have the skills to do the actual automation. Getting somebody in who is unfamiliar with the job, can work, but in most cases you will end up with an off the shelf system that has been customised to perform the original task but come with a large overhead of maintenance that may take more work than the original task.
My suggestion would be that rather than get an outsider to create the automation tools, up-skill and authorise the staff doing the work now to allow them to gradually automate the process. Make sure you make it worth their whiles to automate.
1) As person with business knowledge, vision, plan, etc, I should fully document the business goal and why we're doing it and what we're trying to achieve at the highest level, then work with the developer to figure out what should be developed to achieve that and where to automate.
2) Don't hire outside person or agency, but bring someone in full-time or as a part-time partner for the long term and incentivize them to get better and better?
Seems to be a good idea to separate out the architecting from the actual implementation. Makes sense, because if someone knows they'll have to be implementing, it could cloud their plan for the ideal solution. Similar to separating out design, UX, and development roles.
Does a development agency that focuses on this model exist? Of course they should be paid more per hour (or other unit) than your average, less optimized agency, but the sum total should be less than hiring inefficient agencies.
(P.S. I understand the best developers probably don't want to start or work at development agencies, but assuming there are some.)