Many modern mfds will give true wind using data from simple apparent wind sensors. My Garmin has a pretty good set of tools and displays that I use on my sailboat, using AWA and AWS from the NMEA 2000 network.
I had an early version of the Davis total wx station aboard. In theory, you can do the math. In practice, heading is always changing so math goes from simple add/subtract to differential equation calculus. These systems are designed for terrestrial applications where they are calibrated to North and do not move. Most useful in your home berth.
What is really cool about the home based systems is the machine learning weather forecast. The longer it runs in one area the more accurate it will generally be. It uses ECMWS and NOAA models and runs hindcast/forecast data analytics to tighten the prediction envelope. It is waaaaay more accurate than Environment Canada's forecast for my area; which is akin to a guy looking out the window at times.
In all seriousness, a weather station that shows current weather on a powerboat, while nice, is not as important as it is on a sailboat. A 20 or 30 degree wind shift or 10 knot change in velocity doesn't really change your plans much while underway. I guess it could be helpful in an anchoring situation, though it's pretty easy to tell wind direction close enough for anchoring.
I'd still like a weather station though, just saying that aren't all that important. Not like an accurate forecast.
