If I could find a sub that ticked all the boxes, I would buy it, but so far I haven't. They all either have gluten X, gluten-free but loaded with rice or cassava flour X, or are prohibitively expensive for me X. Someone recommended a coconut flour tortilla a while back, I think it might have been WereBear? I think the brand name is NuCo. I wanted to try them, but not at $15 a pop. I'm working on perfecting my own. I'm getting closer.

My favorite go-to bread replacement is the good ol' chaffle. I don't make them all that often, but it's nice to have the ingredients on hand so I can whip some up when I'm really in the mood. I have shredded cheese in the freezer and I've always got eggs on hand. They're excellent for sandwich 'buns' and for dunking into soup/stew/chili. I know you were looking for store-bought bread products, but these are second best in terms of simplicity, IMO.

There are probably good full-loaf recipes you could try and freeze the extra, but I prefer single-serving recipes and don't really have experience in that realm.

Good luck.