I just use a normal sized vans rucksack. Fits more in than a kids one!
We just use a mini personalised one. Depends what your lo needs to take to nursery, all my daughter needs is a couple of changes of clothes, so her mini one is perfect, she wears it in herself
My kids have both had these for school and nursery. They're a great size and fit everything! https://amzn.eu/d/3A7BwFX
We have the medium sized backpack from my first years. We only provide nappies a cup and one change of clothes though so depends what you need to send in x
@Caroline just got one of those but toddler size!
I’d highly recommend this, we have them for our 18 month old twins, and for our 3 year old for nursery. They are much bigger than most toddler backpacks. But still smaller than an adult’s one. They fit loads in! This is one of the designs we’ve got but they do lots of different ones in the same style/size x https://www.beckyandlolo.co.uk/party-animals-childrens-backpacks-personalised