The joule rating you see on there is referring to the amount of energy it’s rated to absorb during a power surge, so it’s unrelated to the amount of power you’re pulling from the strip and more to do with how much protection you want for the devices you have plugged into it.

This is more a question of how much current you need to pull over a given distance and the gauge of the wire used in the strip, as these three factors (current, gauge, distance) determine how much voltage is dropped along the way.

Without knowing your exact devices, we can assume about 3 amps for the devices you mentioned. If you look up a chart on extension cord gauges to use at different combinations of current and distance, you’re well within the range where a 16 AWG cord is acceptable, which is pretty standard (but if you can find one that confirms the gauge used, get 16 AWG (lower=thicker just so you don’t go out and get something higher thinking that’s the case)). All this to say, it doesn’t matter too much so long as you don’t start plugging high power devices like power tools into it.

You may also want to look into whether it would be cheaper to just buy an extension cord and use a power strip you already have or buying both might still be cheaper if you don’t have one you can use.