What is this seating insert?

I’ve been seeing pictures of this type of seating insert at multiple builds. Can anyone share a link of where you get it from? Is it a stroller insert?
Thank you!


I have found them on ebay and other sites in the past, there is usasully a teady bear in what looks like a 5 point harness.

I think this is similar?

And theres this thread.

Looks closest to this one from Tmart.