I watch all streaming shows on a rowing machine with not-so-high speed and not-so-high resistance. The show keeps me entertained and sometimes I even forget that I'm rowing. Previously I did that with an iPad 12.9" next to the machine, but I've just started watching shows on the Quest 3 and that's way better.
Doing this with a treadmill is honestly a gamechanger if you can't or don't want to do cardio outside (e.g., safety issues, heat, bad weather, etc.)
Even just walking on an incline can get your heart rate into the right zone so you get cardiovascular benefits while being so low in fatigue that you can get a lot of volume in.
Eventually your fitness will increase such that you'll run out of incline and speeds you can walk and you'll have to jog to stay in the zone.
I didn't try exercising with it, but, Quest 2 was getting too hot for me even after a short while playing Beat Saber for example. Quest 3 is much better in that aspect. I can actually keep it on for long durations, and heat isn't a problem at all.
