I’ve read the thread below.  I kind of think, I know the answer, but the laws are so damn confusing.  So I’m going to tell you my planned set up (don’t have the parts to build yet).

PWS upper with 11.85” barrel.  Non-pinned Noveseke “flaming pig”.  Tailhook mod 2 pistol brace.

If I’m correct (don’t have actual parts to measure), this should put me over 26” in length from end of the brace to end of the threads.  

So it’s not a pistol, or a rifle.  And it’s not an AOW?
But is legal to possess and does not have to be registered?

ETA:  PWS has the MK111 (same upper) on their lower and their pistol brace as being 28.5”-32” AOL.

Based on OP's description, if its uses a brace and is over 26" OAL, it is simply a firearm. It is not a rifle, pistol, or AOW.

Rifle - Designed to be fired from the shoulder. Must be over 26" OAL and longer than 16" barrel.

SBR - Designed to be fired from the shoulder. OAL less than 26" and/or barrel less than 16". Must be registered as a pistol in MI if under 26" OAL.

Shotgun - Designed to be fired from the shoulder. Must be over 26" OAL and longer than 18" barrel.

SBS - Designed to be fired from the shoulder. OAL less than 26" and/or barrel less than 18".

Pistol - Not designed to be fired from the shoulder, and less than 26" OAL. Barrel length does not matter. Adding a vertical fore grip makes it an AOW.

Firearm - Not designed to be fired from the shoulder, and over 26" OAL. Barrel length does not matter. Adding a vertical fore grip does not make it an AOW.

AOW - So many possibilities that it's hard to list.

I think that covers it pretty well. If I've made a mistake, please let me know.

The only catch in Michigan, is that a Firearm cannot legally be carried concealed.  Only a pistol can be in Michigan.

PSA has this kit on sale, I'm worried that the 10.5" rail would put me slightly over the 26" length so I could have it loaded in my car.  In the pictures it looks like the end of the rail is slightly longer than the muzzle crown.

https://palmettostatearmory.com/psa-10-5-5-56-nato-1-7-nitride-10-5-lightweight-m-lok-classic-ept-sba3-pistol-kit-w-mbus-sight-set-gray.html

Kit has everything I'm looking for for my first pistol build, already have a virgin stripped lower that has been burning a whole in my pocket eerrr safe for a year lol

I could spend $10 more and get one with a 9" rail and no MBUS sights....

FIFY

Thank you, that is what I meant.