Any idea Why can’t I open it from inside? Are the 2 handles connected somehow
I guess not completely off
View attachment 250369
There's not a lot inside the door. I don't understand why the inside latch doesn't open the door.
Try looking for that thin vertical rod in the square opening on the left. It's about the diameter of a wire coat hanger. You'll need to grab it with needle nose/vise grips and lift it about a half inch to release the door.
If that doesn't work, here's the only other option I can think of. You're not going to like it, but it will work...But I would strongly suggest at least calling a body shop, to see if they can open it first. They'd likely charge you at most $50, if they charge you at all. If you have no luck there, here's the tactical nuke option. Make sure you already have your replacement door handle, because once you've removed the handle base, the inside of the door is now exposed to the weather.
As I mentioned, the handle is plastic, and the rest of the mechanism is metal. You'll need to pry off the remaining part of the door handle, or at least the left side by the larger square opening. The intent is to snap the plastic where the bolt is holding it in. Again, this sounds awful, but you're not going to damage anything other than the handle, which is being replaced anyway. It's a metal bolt, attached to a metal door, holding on a plastic handle. There's a metal nut insert molded into the plastic handle, and the metal nut will break out of the handle. The plastic is the weakest point and will break first. Make sure you use something under your pry bar to prevent denting the door.
Once you snap off the handle, that should expose the vertical rod to pull that up and open the door.
The reason I know this will work is that it happened another time with this truck. My daughter was walking out to get into it, and just as she grabbed the driver's door handle, she slipped on some ice and went down. Well, she instinctively grabbed the door handle harder as she went down, and snapped off the handle at the bolt. Not like what you have, the whole assembly came away from the door. So I do have a little experience at this.
Here's what the back of your handle looks like, arrow pointing to the bolt hole that needs to break...