I sort of looked into this idea. I would use only one or two panels and have these charge a small efficient battery pack. Then use this to charge the devices. This is because most devices will work best when the draw is continuous. I think the 12volt car/cigarette lighter is the only way you'd find a sane level of compatibly.

That being said, automobiles have an obscene amount of surface area and exposure time available for solar energy collection. But even pure EV's have opt'd not to employ the technology (there are a few rare instances).

On a bicycle it is impractical aerodynamically, and you don't give a **** but you'd need an expensive and/or heavy panel aimed more or less at the sun light to produce anything strong enough to generate "charge" on a battery.

Wallmart has a panel 11X18 and ~4 pounds that will put out 18watts. It could be somewhat usable. Flexible paneling seems sloopy to me. Wiggling and waggling is an energy loss. Firmness gives you control and returns your energy.

Some already have batteries build in. That's a plus because you won't need to spend $ on the fancy charge controller. Depends on how far you want to go with it.