Exporting your game is not a big deal at all, trust me when I say you can figure it out along with all of the perfect settings per-platform with little to no concern.
However, if he left some files out or didn't fully build the until game correctly you could have issues. You'll want a game that plays properly and is entirely bug-free. Most releases need updates after release as you discover new bugs and problems, so releasing a game without a programmer on-board is probably not a great idea. Code itself for many games is not always complex if it's a really simple project, alternatively code can be extremely complex depending on who is writing it and how complex the needs are. Did he send you the scripts independently? Or did he send you a final packaged product via a godot scene or something?
You'll have to either find another programmer who is more trust-worthy and just bite the bullet financially if you think the project is worth it, or learn to program a bit yourself just to understand fundamentally what is happening underneath the scenes.
I hope you're able to figure something out!
