There are a lot of recs on this thread from r/femalefashionadvice. Some of the links are outdated, but I found it was able to lead me to other good hats on Amazon, like this one or this one
Popular alternatives to
Coolibar UPF 50+ Women's Ma...
AZMED Maternity Belly Band for Pregnant Women | Pregnancy Belly Support Band for Abdomen, Pelvic, Waist, & Back Pain | Adjustable Maternity Belt | For All Stages of Pregnancy & Postpartum (Beige)