To gather some research I visited Wigan library with my nephew, I spent a couple hours routing through all the picture books, searching for anything gender related. I began to feel as though I was almost looking too hard but when I really looked on everything as a whole a lot became clear - problematic characters are often male, 'Dads' are portrayed useless and silly, Mums are generally the primary carers for the children, most villains are male, and there is a large use of male protagonists. This trip was particularly useful just to open my eyes to particular authors/illustrators which I can further research.
Although I did find some interesting picture books which are much more open minded, whilst breaking stereotypes, these were far and few between. I found that lots of the classic, very popular picture books that are still very common today, seem to only involve male characters which in the modern day is quite alarming. Tony Ross is definitely an author I want to research further as I know he uses controversial characters and I have heard of parents not wanting their children to read their books. Another thing I noticed throughout was stereotyping around gender roles - authoritative figures being male.
I also was introduced to this instagram page which is full of great resources for such topics. I think this is a great page for sourcing helpful, educational books, for families/children who would benefit. I will link below.