Re: Flashlight Finger Loop
Thyrm switchback.
SA Tactical often has them.
I don't know how compatible it would be. You can try have something 3D printed. Or get a surefire or streamlight torch.
The main benefit is in shooting two handed with the torch between your off hand fingers. If you're attending to someone you need to put the torch down anyway, so a lanyard might be of more use
Re: Flashlight Finger Loop
This is a great video from JC at Bravo Tactical on the use of the bungee cord option (on left, in your picture.).
https://www.youtube.com/watch?v=DNa49H3ZgHg