I use it every once in a while when I do a presentation in Teams at work and I need one webcam to show my mush, and another to demonstrate whatever device I'm presenting: I use the cellphone to capture close-ups of the device and focus on features people ask me to show, scrcpy sends the camera capture to a v4l2 device, and Teams uses the v4l2 device as a regular video source.
Seemingly it is still a pending feature, that will be included with the December quarterly feature release ("QPR1"). The only people who are using it now on their phones are running QPR1 betas, which I think first began releasing in September.
KDE connect has been really buggy for me since my most recent Linux install. I can't even send texts unless I use the command line. And it has to redownload all my texts every time I reopen the app.
At least I get notifications 100% of the time, which is the most important use case for me.