I carry a mountain bike in my truck, lots of days I won't ride it due to it just being too dangerous in the areas. So I was looking for options and being that bicycle riding is the magic thing for me health wise I discovered the 'bicycle trainer' and thought it might work in my truck. They come in many variations, mine is like a small foldable bike stand that you put rear wheel axel connected into and the tire rolls over a tension device.I bought a cheaper magnetic roller model from Academy, and it works with my Trek with 29er wheels. It has a tension setting, but you can increase tension with your own bikes gear system too.
So yeap I can pedal away inside my truck, neat benefit of having a bunk is you can just prop front forks on bed, the trainer stand holds the bike great using space between two front seats. It does feel like riding outside pretty close except the device does make quite a bit of noise while riding, but doesn't matter in truck, you can pay more for quieter fluid models. Mine was $130 btw.
I didn't see anyone talking about this, but it can be done and it's pretty simple too. The reason I like this is it gives me a bike to ride outside like normal, also something to exercise on safely inside the truck. Apparently during the COVID lockdowns these sold like hot cakes and so they are easy to find now.