When we were living in the Austrian Alps,our local (very very good!) sports shop reccomended Yak Trax to me:said they were the best.
He was a friend,and also knew that it was very important that I did not fall.
He could have sold me far more expensive types,but those are the ones he told me were the best,in his opinion.Certainly,they improved things and my confidence;) no end.
Unfortunately,I didnt think I would need them back in UK,so gave them to a friend-but have since bought myself some more!
And I think they are reasonably safe to wear in a shop,(and wont damage their floor like spikes) but you do need to be careful how you walk.
If you are quite nimble,suggest take them off,to be on the safe side,but if not,just walk slowly as Elegran says.
And remember,however good your grippers,spikes etc,dont get too "cocky"!
They do not guarentee that you cannot fall,just make it a lot less likely!