I wear wool mittens and keep my thumb in with my fingers.. Game changer. If it is really cold, I'll put hand warmers inside, but usually the wool mittens themselves are good enough. What I would recommend is neoprene sleeves for her toes.

Something like this:

https://www.amazon.com/Hot-Sockee-Neoprene-Warmers-Construction/dp/B076B4PDZR/ref=sr_1_1_sspa?keywords=neoprene+toe+warmers&qid=1669165570&sprefix=neoprene+toe%2Caps%2C113&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1&smid=A1GSSUC09N8EWO

I used to have major issues with my toes and this completely changed that.