I saw a pattern for something that sounds similar just within the past few days - sorry, but I don't remember where and can't find it.
But what I remember, it may have been crocheted. It was scarf shaped, long enough to stretch across your back from wrist to wrist. It had 3-4 buttons and button holes from each end, either side, spaced up to your underarm area. It was wide enough that you could button the ends and your arms would fit thru - you could wear it sort of like a shrug. Or unbuttoned, it was a scarf.
I think the pattern I saw was crocheted, but like you said, you could knit it any pattern stitch as long as it was the right length and width to fit shrug-like. At the 2 ends, place your buttons along one side and button holes along the other.