60GHz is actually poor for through-wall detection as this frequency is heavily attenuated by building materials - lower frequencies like 24GHz or UWB radar would be more suitable for both applications you mentioned.
Why do you say 24GHz and not, e.g., 100MHz? (Apart perhaps from it being within a reserved band).
An antenna large enough to work at 100 mhz would be impractical. That's a wavelength of 3 meters, and incapable of reliable detection of objects less than about 0.7 meters in all dimensions (1/4) wavelength, not to mention the required size of the antenna array
Update: chatgpt told me that the wavelength (3m) is too large to detect humans, antenna size would be impractical, more power would be needed for transmission, and reflections are more of a problem than with higher frequencies.
60 GHz is pretty much Line of Sight. If you can't see it - it will not work.