If you can’t walk on your hands specifically, here are a couple exercises that are handstand walk substitutions.
They require much less balance then walking out in the open, but still train the same muscles and support ability needed.
#1 – Walk laterally in a handstand across a wall. Here is an example.
#2 – Walk vertically up into a handstand and down from a pushup position.
Both these are great exercises most people can do, even if they haven’t learned how to balance in a handstand yet.
If you don’t have the strength to support yourself in these positions yet, you can also do animal movements, which take some of the weight onto the hands which will build up your ability until you can support yourself.