To my surprise, there is no option to add headers to an HTTP request in Automations. We need this option. In the meantime, I'll go back to Workbench :(
Still not possible after 4 years (looking at 2025.2.1). I thought I’d be able to do something simple such as uploading a file from the Resources location on an on-prem instance of FME Flow, to FME Flow Hosted, but I don’t think it’s possible without adding headers, setting to binary etc. Pity. Will have to continue doing this within a workspace.