Have a /furnace command where it would open up the gui of a furnace and you can cook stuff in there while walking around and then later retrieve the items by typing /furnace and taking out the smelted stuff, i know this would be a bit difficult, but it would be amazing, please if you can make this thank you
Its possible, I personally don't know how you would go about starting it (other then showing a furnace view to the player) but it is definitely possible.
What might be a simpler option would be a "remote" ("quantum" if you're nasty) furnace; something where you do a command, click a furnace, and then can access that furnace by doing a second command. One issue I can think of off hand is what happens when no players are around the furnace, since normally it wouldn't run (I think). I suppose if you wanted to you could emulate the entire furnace setup (including the burning of items) and eliminate this issue, but that would be more annoying to maintain.
Well, just like an emulator, i know it would be annoying to maintain but it would be very helpful for not just me but for a ton of people, if anyone could do it, that would be amazing