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Simplify symbolic product

As per the title, I want to simplify this product somehow.

var('i,r')
exp = product(1-2**(-i), i, 1, r)

This can be also expressed as

q_pochhammer(r, 2, 2)

However, the latest expression does not accept the symbolic variable r, but only a real integer.

The main problem is that the actual computation (f.e. exp.unhold().subs({r: 12345}) takes a huge amount of time. Is there any way to simplify this product in sage or accelerate this computation somehow? I've already tried all the simplify/expand methods, but also the combsimp method of sympy.

As a side question, is there any way to use the q_pochhammer function symbolically? Maybe I can use the hypergeometric simplifications on it.