I built a 9mm upper about 10 years ago before the current wave of products were available. I used a RRA 9mm upper, bolt and barrel chopped to 4.5" (threaded for suppressor). I used a VM-Hytec Uzi mag block that inserts like a magazine so I can use it on my AR SBR lower without messing with dedicated mag blocks. I got an oversized YHM handguard that allows my suppressor to fit inside it. It runs without any problems with anything I feed it. I can also stick in on my SBR lower in seconds.
Then when braces and Glock mags became a thing, I did a dedicated 9mm build. I got a Quarter Circle 10 Glock lower/upper. I can't even remember the barrel & bolt carrier I used, but it is 7" long. I finished it just as ammo jumped through the roof, so it has sat untested for years now.