For anyone else also looking for a belt that will lay flat underneath your tops but also doesn't look too casual (like the Beltaway & similar webbing belts), so you may also wear it on top of clothing:
https://www.muji.com.hk/en/product/4550344149577

Available both in black with silver hardware or brown with brass hardware. The holes provided don't go all the way around, but it fits both my 30" waist & 40" hips with plenty of holes to spare on either side. The leather is a little stiff to get the stud through at first, but it does look like it would loosen over time (the tag claims so). Fingers crossed!