Mudd. . try this.
I used a piece of 1" woven strapping for an example.. and it may work fine.
I started with a piece about 20" long. I cut a 3/4" slit in the center about 8" from one end, using a sharp (single bevel) wood chisel and a bit of effort. Tuck the longer end thru the hole.
Then I put that on my wrist such that the part that went thru the hole is on the inside, toward my body.
Then I pulled the pieces to extend them. Wrap the inside piece around the bow string and let it overlap about 3/4"
Hard to see here but the wrap is from the inside toward the outside. (Bow side to outside)
Then wrap the other end the other way, right over the first wrap
Fold it down and pinch with thumb and forefinger or however you need to do it to make it work.
I took pix so that you can see what I did, but they are pretty generic. You have to make it fit yourself. You can draw back quite a bit of poundage this way as long as there are two wraps.
The piece I had for the second wrap is too long. That needs to be adjusted shorter, to fit your needs, but it shows the gist.
Release by just not squeezing.
I don't know what capabilities Jacob (or others) have with his hand so I am only guessing that this will work for him. It does work though and is easy to make.
ChuckC