I worked in body shops off and on....The last body shop I worked in, I worked on fleet vehicles....Yes, they do make a 2 part adhesive, or epoxy that glues, door skins,bedsides, etc...I don't remember what the cost was but it's not cheap!! Then you have to have the special caulking type looking gun for the 2 parts. But yes! you could grind it to rough it up, rough up your metal patch and glue it in, for a temp fix but, probably cheaper to find another door in the long run. Most newer truck bedsides are glued on. I know chevy was in mid 2000's. I glued a ton of them. one weld in the back by the tail gate and one weld up by the cab end, the rest of it is glued.
If your just wanting to do a quick, who cares patch job? Use expandable foam that you get at the hardware store in a can. Spray it in there, cut the extra off with a knife or a hacksaw blade, spear some cheap bondo on it, and good to go for a little while, or just spay paint the foam if you just want to seal the hole. They use the same type of foam(a little different) in cars anyhow. If you try this route? Make sure you don't fill the door!! The window won't work. Take the inner door panel off and make a cardboard like wall so the foam doesn't get into the door tracks and in the way of the window.....This probably one of the most hack things you can do...But cheap...or ? use duct tape! Ive seen that before...I've also seen people pack the hole with newspaper and smear bondo over it.
Be creative!! I doubt that you want to fix it right, that's why I gave the suggestions that I did. I understand the "if I can just patch it for now who cares" very well! All my junk has been bubblegummed for years!!