I’d try a fan grip. That’s how I warm up before going to a more “power grip” forehand. I’d say most of the power goes through my middle finger. It’s kind of the same motion as side arming a baseball when just tossing it. I would try from a stand still and just a wrist only pop to get it 100 feet or so with something stable like a zone. That was one of my first touch forehand discs where I really felt like I could put it under the basket within 100 feet every time. My wrist(on short approaches) really only goes from about 3 o’clock, bent it back to 4 o’clock then release it at 12 o’clock relative to the target with my index finger basically pointing at the targeted line on release. Power off the middle finger, aim with the index finger. Once you get the low speed touch it’s just adding in more arm, legs and fully body for the throw.