My plan is to inject onto NMEA a bunch of PGNs that are displayable on MFD,but for which i dont have NMEA capable sensors (eg fuel tank, water tank, black tank, engine room temp, humidity and baro, domestic battery, generator battery, )..let the fun begin!
E.g. Garmin GMI 20 has definable pages for 4 values on each page. B&G vulcan has also configurable data values. So yes, MFDs should have them othervice they are not MFD - just SFD (Some Function Display).