Hi RehabRN,
Even honest manufacturers may have little knowledge about what is inside the mattresses they sell. The stores that focus more on the materials in a mattress than they do on the brand name of the mattresses they sell are the ones that I would generally prefer to deal with.
The better options or at least “possibilities” (because they will all need more research) I’m aware of in your area are listed in post #2 here.
It will tell you more than anything else about how long a mattress is likely to last compared to other mattresses (see the guidelines here).
Even if there are reviews for a specific mattress they wouldn’t tell you anything about how a mattress would feel for you or whether it would be a suitable choice for you in terms of PPP (see post #13 here). A mattress that works perfectly for someone else or even a group of people may still be completely unsuitable for you to sleep on.
Phoenix