I know, but they all require granting full screen recording access to third party software on an ongoing basis, which is a complete non-starter in my case.
Almost none of the YouTube/blogs recommending this mention it or seem to be aware (or have just clicked through and granted the permission without thinking about it), but it absolutely does require screen recording to operate.
The DisplayLink driver requires your admin password to install, and installs itself as a background process that records the screen constantly in order to software render the extra display. There are other similar products, they all work this way.
I am not sure using a screen recording api/permission in a driver is really the same thing as "screen recording". I.e. The recording is not being saved to a file. It's just a way to access the display pixel buffer.
But if that makes you uncomfortable, well you're going to have to pay$$$...