Why this mod
My gameplay is focused equally on active sims and townies, and I've found that townie toddlers do not do well when it comes to autonomously learning the essential skills (potty, walk, talk) because they depend on idling/busy/snacking (I kid you not ) caretakers to learn said skills.

One alternative I found while searching online, for toddlers to "learn to walk" autonomously, is to bring in the game the "push walker" object, which would free up toddlers from having to wait on a caretaker to put them into the store walker object. With a functional push walker object in TS3, toddlers should be able to walk to the object, grab it, and start learning to walk by walking across the room.

I am thankful to the Totshop TS3 store (found via @Renlyna) that has released this one perfectly fitting deco TS3 push walker, along with a pose for illustrating how it would work, were it ever functional:
https://totshop9.wixsite.com/totshop/push-popper

Next Steps
Now the next steps to make push walkers happen in TS3 are:

• TS3 toddlers animation queen @TheSweetSimmer had shared that this would be quite the complex functional object mod, because there is a sequence of multiple animations to be custom created in Blender and queued in the code, and that due to their height, it requires a lot of iterations to get toddler animations right. Having never opened Blender, this sounds like a serious challenge to overcome.
• Hopefully the "push walker" can become a script class to turn deco walkers into functional pusher walkers. If possible, it'd be nice to have 2x types of "walker" animations to accommodate the creativity of CC creators: 1x where the toddler has hands joined together to hold the walker, 1x where the toddler has hands apart to hold the walker. See images attached to see the difference. I've seen quite a few custom store walkers on ATS3 Sandy's website that could be fitting for the "hands apart" push walker animation ("dog shaped" walker, deco trolley object). I have also seen "toy pram" CC that could fit the "hands apart" animation.

And of course, the plan is to make the usage by toddlers of the push walker object, autonomous (tunable).

To be continued.