I'm actually gonna implement this setup (I'm looking out for used Mac minis on my local equivalent to eBay this week), for when my iPad Pro and Magic Keyboard get delivered over the next couple weeks.
This means I'll be able to use the setup for sketching and illustration, video-editing, note-taking and other typical iPad tasks, but then also be able to hook it up to the headless Mac mini (which I plan to stash in a cupboard) and use Xcode and other MacOS-only applications.
No idea how well this is gonna work, but I'm certainly looking forward to illustrating again - something I've barely done for the last few years, and which used to be a large and very satisfying part of my work (in the days before narrow specialization was such a thing).
I had noticed that, and that's why I was wondering if an HDMI dummy (a simple device that pretends to be an HDMI display) could be the primary display, using sidecar so an iPad would be the secondary display, mirroring the primary.
Just thought I'd note that in case this setup is very important to you before you buy your Mac Mini. I don't do any sort of graphics design and video editing, but people seem to be generally pretty happy with it for those purposes.
Also, many of the free drawing Apps in the App Store are actually very full-featured and feel fantastic to draw with (please support them if you like them), which is what I settled on in the end. The only thing that I miss about my Wacom Intuos is the textured surface.
Edit: removed repeated "a couple of months ago" and "in case", moved things around a little.
For video I’m gonna try the iOS application LumaFusion - this is new to me, so I have no idea how it compares to apps like Final Cut Pro or Premiere, that I’ve used in the past - but I’ve seen some encouraging YouTube videos showing editors using it, at what seems to me blinding speed.
The Mac mini would only be used for Xcode and other stuff that isn’t available on iOS (or iPadOS).