For any given client of ours, I'd like to be able to fetch their Shopify store revenue by month for the at least the past year.
I know I can create reports and see/export them manually through the Shopify Partners UI (assuming the client has given me access), but I'm looking for a way to automate this. Any suggestions?
You would need to call the API to get all orders and then aggregate them yourself. Shopify used to have a ShopQL API, but they deprecated it.
There are a number of 3rd-party reporting apps that could help automate this for you.