200D is much newer, but less well supported by ML. I own this cam and am actively working on improving it. 200D has DPAF, which means considerably improved auto-focus, especially for video. Also it can run Doom.
Are there any ML features in particular you're interested in?
So ideally I'd imagine getting a second-hand 600D or 200D and having a similar setup. We did have a setup (previously) where a GoPro or mini-HDMI campera is captured and then processed by a RBPi 2/3/4, but this seems an overkill compared to the DroidCAM Setup.
And, of course, the optics on the 600D/200D are expected to be much more correct than those on an iPhone or similar phone/mobile device.
Thanks for your kind attention.
AF with 600D in liveview: Phase detection only. Focus hunting galore. 200D comes with usable DPAF.
I prefer 250D for streaming. Dual display support, no 30 minute limit for HDMI out (but cam display will go dark until some button action).
IMHO even 800x600 is okay for most streaming needs. And particularly when sound quality is of primary importance.