It really doesn't matter. Reason being, all floating floor manufacturers REQUIRE, a Tee Molding transition across all doorways, less then 4-5 feet wide. The individual areas must float independently from one another, or it is highly likely it will eventually separate across or through the doorway. Hallways are a must have Tee molding

Well, from experience, I can tell you that our idiot GC DID NOT put the floor running all the way back under the fridge, freezer or DW and it has already caused problems. The first was aesthetic... The fridge does not sit directly on the floor and you could see where the floor ended and the substrate was. That was ugly, let me tell you. Fortunately my dh is getting better in his woodworking skills and he used a left over piece and custom built a toekick to match the rest of the kitchen and installed it under the fridge so now you can't see the substrate. Secondly, we had to move the freezer and damaged the edge of the laminate trying to get it "over the hump". Fortunately you can't see it. Also both the fridge and the freezer are built in and screwed in place so fortunately, unless they are ever replaced, they will never need moving again LOL. The lack of floor under the DW was also solved with a toekick but we had to build it up so we could attach the top to the underside of the counter. All in all, IMHO, it's better, probably cheaper, and certainly less hassle, to run the floor all the way to the wall.

Ok...now the elephant in the room would like a word: Can you source the SAME floor? I mean the IDENTICAL floor? This is first and foremost your #1 priority. Everything after that is a moot point. Most 'man made' products (such as laminate and engineered hardwood) have a "shelf life" of 18 - 24 months. Your project was completed about 2.5 years ago. There is a greater chance that you will NOT find the original product vs. finding it. So....therein lies the rub. If you can source the original product, you can add it to the original floor at the junction where it stops. You may have to pull that last row if it is "cut" (you always need an intact tongue/groove to continue). The HDF core is what limits the "run" of a product - as well as the type of tongue and groove. The 31 linear feet is getting very close to "maximum" run. And the 31 linear feet would need to be the LONG EDGE of the plank...not the short edge. Go ahead and google your floor (you will need to have the box in front of you to find the maker and the "line" of your product). Punch in the "line" and then add "installation instructions" to the search engine and see what you get. Many HDF cores have a 30 - 35 ft maximum run....on the LONG edge. And the short edge can have a maximum run of 25 ft. These are "common" numbers we see with HDF core floors. And just so we are clear - laminate is inappropriate for a kitchen. It has a life expectancy of 3-7 years. The 'high end' laminates can reach 7 years....but then they can die a tragic death at the hands of the dishwasher. Good luck. First things first: find out if you can SOURCE your original floor. Without that identical floor, your question is only hypothetical.

In my experience, the main reason MDF/chipboard/OSB subflooring squeaks is due to internal separation of the product. I have worked on several homes with subflooring listed above and was not able to fix all the squeaks. I used several products designed to insulate/separate the subflooring material from joists, screws designed to be installed through carpet, through the subfloor and into floor joists, and adding fasteners. The only sure fix was to remove the material that squeaked and replace it with plywood.