I learned about the app Transloader thanks to a MacStories article that popped up in my RSS feed today. Transloader lets you send a URL from any Mac or iOS device you have to your Mac, and the Mac will download it, send it to an app, or pass it or the downloaded file to an Automator workflow.
Saving downloads to my NAS is something I have longed to do for ages. I have tried to make iOS Shortcuts that do this, but I never got anything to work reliably. Transloader makes this task possible, though it ropes my Mac into the process. Fortunately, it even works (albeit with delays) if you don’t keep your Mac on all the time.