Warm pyjama / onesie recommendation for a 10 month old who always kicks off the duvet?

She hates sleep sacks, we've tried. She thinks it's a duvet, tries to kick it off and gets her legs stuck upwards inside the sleep sack, and then all hell breaks loose.

All the onesies in the shops are just regular thin ones. Nothing very thick that could be used to sleep without any covering, especially in winter.

I saw "sleep suits" on Amazon but they look very thin also.

Any ideas?