Phone Link for cell phone calls with a headset

The phone link app can connect to my Pixel phone pretty well, but when I make a call through the app, the headset does not kick in. I have a Bluetooth headset connected to my computer. The computer sees it as both an input and an output sound device. But when the call is ringing, it only makes sound on my phone, even though it shows the computer is the Bluetooth device it is connected to.

I have tried a dozen different variations, and nothing works. Switching Bluetooth devices on my phone doesn't always work, as my phone will switch back to something else, like the computer or my watch, or just the phone.

What is the best way to use Phone Link and have a headset to talk into?