A nice item I picked up from Ben at Art of Fishing back in the day. The Little Fish Holder by Osamu’s Factory.
I’ve not promoted the use of fish grips before because I’m concerned with the potential of anglers using them incorrectly and damaging fish that are destined to be released. But I have to admit that, used correctly with a hand to support the weight of the fish under the belly, they can certainly help to reduce the chances of dropping a fish and injuring it. Could also be useful if you regularly encounter weever fish.