I designed this smaller foregrip a while ago for a pistol I was working on.
It is nearly vertical, at 83°.
Use a 6-32 x 1.25" bolt to mount the Picatinny.
The Mlok uses 2x 4mm x 20mm screws with mlok t-nuts.
Update 10/25/2022:
Added a Picatinny_V2 that is all one piece for sliding onto a rail.
Added the mlok STEP file as requested.
Increased the size of the picatinny cutout on the Picatinny versions as I found it too tight.
The author hasn't provided the model origin yet.