Baby flat head

My baby has a flat head , we try to do as much tummy time as she’ll let us but she really hates it . She’ll be 5 months old and we’re keeping her off the back of her head as much as possible but I have been looking into pillows that will help while she sleeps . Does anybody have any experience with these pillows ? If they work ? Or any experience with babies with flat heads , and what you did to help and the outcome. Thank you in advance ❤️

** I know pillows are not recommended! I’m posting this for other moms experiences with babies that have flat head and/or used a pillow.