A big lesson I learned, (at my own expense recently), was.
Never under-spec a prototype.
If there are 2 or more, pin compatible and software compatible, versions of the same device, get the better spec devices e.g. more ram or better speed etc etc for the prototype,
Otherwise you can end up with a batch of unless boards, or ones where you waste hours trying to optimise the code to work.
If you over-spec, it will cost 50% extra on 10 prototypes, but at least they will all work, and you can optimise later to see if you can get away with cheaper device(s) in the final product.
Post here first, or if you can't find a relevant section!