Thirty years ago, when I was raising my kids, there came a time, around the five months old age, when the baby was wanting to be upright and practice the movements that would eventually get him walking so we walked him around, small fists firmly clutching our fingers, and around and around and around and then plunked him (I only had sons so I tend to think in this pronoun) in a Jolly Jumper suspended in a doorway and then into a walker, same idea, but on wheels that gave mobility.
Grandbaby is now of that age and the Jolly Jumper is on site but the walkers are – BANNED! In Canada. Not in the US or Britain. It seems kids fell down stairs in the walkers.
Well, darn. I remember those walkers as being beneficial to the kid and the parents. Maybe some other baby boomer Grandma or Grandpa is working on a design that will be safe around stairs. Width must be a factor. Likely a matter of inches.