It is not unusual at all for owners to contract separately for hardscape. If you have them subcontract, you are just adding a cost layer. The two should absolutely meet though, along with you, to coordinate and plan the project. I would interview hardscape folks the same as I would a PB, then take your choice and get the parties together. That is of course, if your PB will not do the type of decking you want. Our situation was different. Our PB was a landscape contractor, who built pools using a one-man PB, but the contract was all handled by the landscape guy. We needed extensive hardscape above and below the pool site.
Though I don't disagree with Pool_Medic above. Pavers in freeze areas aren't as simple. And although polymeric sand will last a little longer, the repeated daily drenchings with water will cause it to wash away faster than if it was in a non-pool environment. This shouldn't discourage you from doing them, but do it right and know they will require some upkeep, whereas unfinished concrete only needs an occasional powerwashing. It will crack some but will last for a LONG time with just the powerwashing.
We have about 1500 SF of pavers completely separate from the pool area with polymeric sand, in a freeze environment (though not MI). It has an 8-20" base of stone dust depending on the location. I can see that is rises and falls about 1" in some areas over the winter due to frozen ground. I see it primarily where I pile snow and in that area the snow cover keeps the pavers colder. Allowing the ground to thaw more slowly. Once that snow melts, that area is usually humped up some until the ground there thaws also. As a result, I'm sure this also causes the polymeric sand to get loosened and come out over time. It also has created some very slightly unevenness afterwards. The main body of pavers that is fully and evenly out in the sun doesn't seem to have that issue. It may raise some too but it's not identifiable. I'm not an expert by any means, just sharing some personal experience from our 10 years of pavers here.
Our pool deck is concrete that I'm letting go natural. It was stained originally. It has some cracks, which showed up on about day 2 of installation (sun unexpectedly made a strong appearance during the pour and the mix was made too dry). But other than that, I do nothing to it. It's also smoother to walk on than our pavers if you have sensitive feet. Though some pavers are smoother than others.