I know its been a few months since the quest 2 has been out, but i can't seem find a good knuckle grip. For the quest 1 had a neoprene and nylon based knuckle grip, it was awesome, it didn't get all stretched like these silicone based ones.
The default straps work well for me. The only time I feel at risk of throwing my controllers, is when playing Beat Saber. But use a "cup" grip that prevents it from happening. I don't hold the handles like a sword when playing Beat Saber at all.
That being said... those grip mods look splendid. I may have to upgrade soon!
I'm using these and they are great! They are the AMVR ones. I have used the velcro based ones and I strongly prefer elastic. Definitely not a gimmick. Especially in games like Beat Saber they are essential. Both the extra texture and the strap make it much harder to drop or slip.