This is an interesting point because with the kind of matter density needed to even approach the Bekenstein bound, it seems like achieving near zero temperatures would be increasingly difficult.

Said another way, the Bekenstein bound is a limit based on the amount of information contained not just in a volume, but also with a given amount of energy. IANATP (I am not a Theoretical Physicist) but it seems like, according to the Bekenstein bound, lowering the temperature might reduce the theoretical amount of information available.

Anyway, yeah, the Bekenstein bound is purely theoretical, there is not, and probably never will be a practical demonstration of it.