Not the answer you're looking for but we just put a cap over our double chimney. Our area has terrible pollution problems and, although we liked having fires, we're happier not contributing to the area's bad air.
Just guessing that this is to get the conversation off of Indeed, for whatever that is worth.
BTW: I use Signal to stay in touch with my far-away family. It's pretty nice. Rumor has it that it was originally built by the CIA (the US spy organization).
I see mounting to a stud as something useful if the outlet is expected to get a lot of use. The “wings” of old work box might possibly dig into the drywall and become loose. In this case the use level will be low, right? Besides, attaching to a stud is work intensive, and I believe that using an old work box like this is up to code. I’ve used them a number of times.
EDIT: Also about the caps… I try to observe a “code plus” approach and wrap caps with friction tape (NOT the plastic electrician’s tape). That stuff will provide a little more protection for decades.
Great! I’d also explore properly attaching the blue box to the drywall, then using a box extender to cover the space taken up by the melamine. This way the outlet and cover can be securely attached.
So the the third photo is with the melamine cabinet removed? If so, you are so lucky to have found it now. That old outlet looks like it was shorting. Major fire hazard there. What does the back of the cabinet look like?
The old outlet should never have been buried like that. I’m not an electrician but my understanding is that the outlet should have been removed, the wires properly terminated (with caps or the like), the box covered with a plate cover, then the back of the cabinet should have had a hole cut into it so access to the cover was still possible with the cabinet in place.
Plus: what’s the deal with the blue box? Was it never properly attached to the wall? Did the original installer mis-cut the cabinet hole and instead improperly add a new box?
Our dog used to love jumping after balls at the beach. We’d do it often. I regret it now. In later life he developed major hip and leg problems. It took thousands of dollars to get him to where he could walk without much pain.