Get offset minutes from timezone (string) with NodaTime

You need DateTimeZone.GetUtcOffset(Instant):

public static int ConvertFromTimeZoneToMinutesOffset(string timeZone, IClock clock)
{
    DateTimeZone zone = DateTimeZoneProviders.Tzdb[timeZone];
    Offset offset = zone.GetUtcOffset(clock.Now);
    return offset.Milliseconds / NodaConstants.MillisecondsPerMinute;
}

You could leave off the IClock parameter and instead use SystemClock.Instance in the method, but that leads to code which is harder to test.