So hard to find any right now, everything is crew neck. I got a couple of these from Amazon and I like the fit! True to size. They have a seam up the back and rounded hem.
Popular alternatives to
Amazon Brand - Daily Ritual...
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)