Briefly, there are actually 3 bands being used with 5G technology.
The 5G low band (600-700MHz) can cover hundreds of square miles with service that ranges from 30 to 250 megabits per second (Mbps) in speeds. That frequency also readily penetrates buildings; think old analog TV signals.
The 5G mid band (2.5/3.5GHz) can cover a several-mile radius that currently ranges from 100 to 900Mbps. That frequency is close to Wi-Fi so think about what Wi-Fi can penetrate, e.g. interior walls and brick but not so much concrete.
Finally the 5G high band (millimeter wave/24-39GHz) works within a one-mile or lower radius to deliver roughly 1-3 gigabits per second (Gbps) speeds. That frequency won't penetrate your hand! This is pretty much only useful in arena type scenarios, e.g. football games.
So the speeds of the low and mid band signals are Ok (250Mbps) to nice (900Mbps) but the real high speed band is very limited in penetration. Think too that to get 900Mbps to even one device will require a gigabit backhaul.
Oh, and not all "5G" phones (don't get me started on AT&T's "5Ge") have radios in all three bands.
Double oh, not all "5G" carriers use all three bands.
Don't rush into 5G mobile phones.