I think Chantal should consider kaftans. I was looking at them for myself, for wearing around the house, because I haven't lost the weight I gained in lockdown, and I wanted some things I could still wear if/when I lose weight. Most of them are one-size-fits-all, but you can get SML kaftans (I imagine they extend the length to accommodate bellies and butts).
Anyway they are flowy, and can be in gorgeous fabric you can wear to a party, or more practical fabrics. If she's going Temu, there are *plenty* available for less than $30, but Etsy has a bunch, especially custom-made ones. You can look up Montserrat Caballé the opera singer doing a duet with Freddie Mercury....she was a gal of substantial size, but wore the loveliest caftans.
I wouldn't think there'd be any religious objection to caftans, right?