My Asus laptop came with their own version of this preinstalled. I had to install the corresponding app on my phone, but when I tried it out, I had no noticeable amount of latency for anything you would use a webcam for. It was over a relatively fast WiFi 6 connection though.
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.