It never worked unless you were walking on the street. Expensive too, I heard $20 per antenna. Millimeter is good for fixed antenna and delivering internet last mile to homes. Verizon bought into it millimeter while TMobile focused on mid bands, why T-Mobile is faster on average than Verizon. People use their phones indoors.
Examples of Android phones that often support mmWave 5G:
Samsung: Many Galaxy S and Z series models, including recent releases.
Google: Pixel phones, especially the Pro models.
OnePlus: Various 5G phones, including the 10 Pro, 10T, and Nord series.
(etc)
Apple should get their shit together.