I also made soakers/diaper covers out of them, mostly with long legs so the diaper cover works as long pants.
Two sleeves sewn together and a high-rise waistband.
I also made matching vests to keep the baby's center warm. Spills pretty much roll off felted wool, so it stays cleanish and pretty dry even without a bib.
You probably don't want really thick felt for these uses. Alpaca felts very well, also cashmere, and the holes that make the sweater arrive at the thrift store mostly disappear.
i've seen but not made hats.
i always wanted to make a patchwork blanket from felted sweater scraps, but never got to it. I've got a big bag left from making diaper covers, mostly cashmere. Pillow stuffing, I guess.
Probably there would be
enough scraps left over from the mittens to also make little animals.