Glock has been offering factory direct mill guns for the RMR and shield footprints in Europe for several years. They have since added a factory direct mill gun for the Leupold DPP footprint. At this time they are available in the US only for Eli and military sales. In particular, I am aware of at least one army special operations unit using GEN 5 Glocks with the factory DPP cut And one highway patrol organization in the southeast United States which is adopting the same combo.
Smith & Wesson publicly offers an M&P 2.0 factory direct milled for the ACRO cut, which again is LE Agency sales only at this time. But if Smith and Wesson offers that You can bet Glock will offer it as well.
That’s the number one and number three suppliers of service pistols in the US LE market. SIG will be a tougher sell since they are also an optics company and want to keep their gun customers using their optics. In fairness to SIG their ability to provide a complete package of done with factory mounted optic has helped overcome some of the bureaucratic inertia for agencies looking to adopt red dot pistols. However, as we saw with the CBP solicitation’s RMR/DPP footprint requirement, if a big enough customer asked for P320s factory milled for the ACRO SIG will make it happen.