We had the same fridge issue! I tried a lot of things, and honestly, the approach that has worked the best, is to just leave him alone when he's in the fridge. He leaves, of his own volition, faster than he did when I tried to "get" him to leave. I do have to remind him to shut the door when he's done, though. I've told him enough times that we don't want the door open too long, because we want to keep the cold air in, but, really, how easy is that for a 17 mo to understand? And I think he understands a LOT of what we say. He does understand that we want the door closed, I believe, but the "why" is pretty complex, imo.
Anyways, I decided to try the "non-coercive" approach to the fridge situation, and he does indeed decide on his own that he's done playing in the fridge. I'm sure that its easier for him to leave sooner when I'm not constantly distracting him from his important work rearranging the fridge

I just decided that I'd see it as, he obviously has some reason for wanting to look in the fridge. Let him do it, and when he's done, he'll follow suit, and close the fridge like we do (though, like I said, I do need to remind him to actually shut the door once he leaves, and he's happy to do so).
Dp isn't quite sold on that idea, and I've noticed (casually observing) that ds spends longer in the fridge when dp tries to get him to shut the door. (dp explains, and redirects, and all that, respectfully).
As far as handling unsafe items, I tell ds that something is "unsafe" (dangerous doesn't seem quite honest to me for some things, kwim?). And I'll tell him why, and I try to find a reasonable substitute. But...if that doesn't work, I'm ok with him being unhappy about it. I mean, if there's a way to let him touch it supervised, that's great. But, I really am not comfortable with him playing with a knife. So... imo, thats not disrespectful. Well, as long as I try to be empathetic that his desire to play with it is an OK desire. kwim? "I can see you want to play with that knife. It looks like fun to you. But it's unsafe, and not to play with. Perhaps we can find something else that would be fun to play with."
I dunno- maybe some people would disagree with that? But really, if its an honest to goodness UNSAFE thing to play with, I'm ok with saying no (I don't really say the word "no"), and letting him cry if that's what he feels like doing to respond to that.
Oh, another thing- I give him information all the time, about everything, whether I expect him to respond or not. Meaning, for example, if he's playing with something that's loud, while dp is sleeping (he has way different hours than we do!) I tell him that its loud, and daddy's trying to sleep. If he continues playing with it, that's fine. Just giving info. Well, recently, there have been a couple times that I've said that, and he did stop playing with the loud toy right away, and looked for something else to do. I was actually pretty surprised!
I guess I'm just saying that because it happened recently. lol. And at first, I thought that by "telling him to do something" and then not enforcing it, I'd just send the message that he didn't have to do anything that I said, and that he'd NOT do anything I said. But that thought didn't really mesh with my parenting philosophy, AND it doesn't mesh with reality, imo. I've found that just the opposite is true. He's quite happy most of the time to go along with what I'm asking. and if he doesn't, he has a good reason, kwim?