A bluetooth or WIFI dongle and one of the apps such as Torque provides all sorts of information including voltage and boost. I enjoy monitoring coolant temp, manifold pressure (boost), hybred battery % of charge, GPS speed and altitude, voltage and intake air temp but there are many more data points available.

 

I've used this for years and still have the turbo gage.

 

I have a Garmin dongle that does the same with the Garmin Mechanic app, but I don't think they make them anymore. I've had it at least 15 years.