The fs nosegrind one is a variation of the regular frontside 5050 where you only grind on your front truck. The technique involves balancing and grinding on the centre of the front truck’s hanger – balance is the key here.
It will probably help if you can ollie into a nose-wheelie already, as the process is virtually the same. You’re also going to need to be comfortable ollieing at speed and dealing with the friction of grinding.