First of all - how COOL about the Zoo - I would love to be able to do that!
If it were my daughter, I would not give her a walking device. Why would she have to concentrate any harder to walk, then she would when she is mastering anything else - and SHE is used to her vision, so I guess I don't understand that concept. I wouldn't worry about her walking yet anyway - she's got a lot of time.
I wish I could remember exactly how it was told to me, but one of the first pediatric opthamologists we saw when my oldest was a baby told us something about ocular albinism/albinism being a different kind of visual impairment - meaning there generally is no blurriness, just less detail, not being able to see small things from far away etc. but my son shouldn't have any problems developing because of it - crawling, walking etc.
Now if they were trying to walk an obstacle course - different story. LOL