ODB2-port gauges can only display sensors that are:
a) installed on the vehicle
b) monitored by the ECU
c) reported by the ECU via a PID
So, no oil pressure, oil temperature, or EGT on a 2004 BEW, for example, 'cause no sensors.
Because there's a MAP sensor boost can be reported, although it's slightly susceptible to the weather, since the MAP reads absolute atmospheric pressure, which varies a bit with the weather, altitude, etc. Actual analogue boost gauges read relative pressure... the manifold pressure relative to whatever the current barometric pressure is.
Also worth noting that the refresh rate over OBD2 can be a bit slow... maybe 1-2 Hz. Some find that a problem as a boost gauge.