I definitely have many a day that I still watch something else on the tv and just watch zwift on the laptop.

Zwift is offering a free trial for all Strava Premium members at the moment. I think even if you have a dumb trainer, I'd still give it a shot. An ant+ usb dongle is $20. I needed an extension USB cable to get the dongle back by my trainer, but ymmv - still for $25ish, not a bad time to try it out.