I know a couple people who are doing the DSLR or mirrorless to HDMI->USB thing. The results are indeed nice. But, to be honest, I have a Logitech 920 webcam and some decent lighting and that handles even making video recordings pretty well. "Can't buy" seems like a stretch.

And for anything I'm streaming I'm frankly more likely to have issues because my Internet upload sputters than anything to do with the camera. And with the Logitech webcam attached to my monitor, the whole thing "just works." If I had a newer model of Canon, I might have tried it but as it is I'd need to buy a converter.

If you're using it powered all the time, have you checked out the existing plug in "fake battery" options? Here's one example: https://www.amazon.com/Glorich-Replacement-Adapter-Cameras-F...

What resolution does it produce? My Sony α6100 yields only 1024×576, which is not great, though still better than any laptop webcam at 1920×1080, or mostly even a phone or tablet front-facing camera at 1920×1080.

(The Sony α6100 is also quite happy to run on USB power indefinitely, no fancy battery arrangement needed. I’ve used it thus for multi-hour webcam sessions, and plugged into a wall charger for multi-hour recordings, where its battery would otherwise be depleted after about 100 minutes.)

Another thing to be aware of when using fancy cameras like this is the latency: you’ll get added latency of 100–400ms, which is easily into the disconcerting zone if audio and video are out of sync by that much, so you may need to do things like add a corresponding delay on the audio, if that’s connected to the computer directly (which will give much lower latency). OBS Studio can do this. I don’t yet have an HDMI capture card, so I’m not certain about it, but the impression I’ve received is that latency will be much lower with a decent capture card than the USB/PTP approach, though still probably higher than your webcam.

I'm not actually sure what resolution gets passed through the USB cable. I would assume it's either native resolution or at least 1080. But to be fair I'm mostly recording in 720p 50fps, since the 4k is cropped with the EOS R and I felt more fps is better for webcam footage (the other modes are capped at 30fps (25?) or have a crop). Besides, people don't need to see my face in more detail.

I haven't seen any noticeable delay in the footage so far, but now that you mention it, I'll definitely keep an eye on that.

The EOS R can draw some power from USB, but it doesn't seem to be nearly enough, or it doesn't work while recording or something.

Latency through a cheap chinese capture card is like a 12-17 ms for me.

To mount a camera on my desk, I'm about to purchase this "Neewer Tabletop Light Stand", and a mini ball head with standard 1/4 inch screw for angle adjustment.

I can't vouch for it yet, but hope it arrives and does the job. There's other similar products in other sizes by other brands.

[1] https://www.aliexpress.com/item/1005001657723138.html

You can buy a dummy battery with a/c adapter.

Sony also updated their software in august and now support using their cameras as webcams without a capture card.

Fuji does something similar with their cameras. I can use their webcam software and get clean video output when I connect my Xt3 via usb to my pc or laptop. No need to purchase extra unnecessary dongles.

I was quite excited to try this when Fujifilm first announced it, but then immediately dissapointed when I found out it does not support the x-t30.

Yeah, I ended up trading in my old XT1 and picked up a used XT3 at a great price which helped. It's frustrating that not all models are supported though.

Have you try to use the max aperture, and let other enjoy the bokeh? ;-)