Agree that the corner pantry will be more reach in than walk in. Do remember to add a light inside, overhead just inside the doorway or over the door IF you go that route. If all your doors are either white or the same wood or the same color as the walls, a pantry door wouldn't necessarily need to match the kitchen cabinets.
Your mudroom will be the first thing you and your family and your "back door guests" -- closests friends and family see regularly -- consider making it something to be proud of instead of something to be hidden behind a sliding door..
Would definitely move the door to the to the mud room from the outside/garage so that it is across from the entry to the mudroom from the kitchen -- clear straight walk path equal less wasted space, putting the hinge of the exterior door on the powder room side of the wall. You could do away with the bench along the left side of that walk path because the entire wall between your mudroom entry door and the powder room could be usable, uninterrupted, by your bench wtih hatrack/backpack storage, keeping the clutter contained and "hidden" behind the door as it opens. Your powder room door would also be "hidden" by the mujd room entry door as it opens.
Haven't yet taken the time to read thru the other comments but, in case it hasn't been mentioned, you might seriously consider using that corner you're currently considering for a reach in/walk in pantry as a part of your powder room (toilet nook): have your toilet and sink face each other, preferably with a small high window in the exterior wall between them). This would mean the powder room would be wider but would not need to be as deep (no need to walk in front of, only between toilet and sink).
Changing the powder room would also mean that your toilet would not be visible if the powder room door is open and it would increase your mudroom storage space by however much space you had planned to allow you to stand between the toilet and wall -- you'd also actually end up with more space for standing because, instead of separate space, the standing space would be shared -- nearly doubled.
Along with changing the powder room, You could still add a deep refrigerator height vertical drawer next to the refrigerator -- between refrigerator and powder room wall -- to be used as a pantry (better yet a pair of vertical drawers, upper and lower) -- as wide as you need for whatever you intend to store there.
You could also create a modified kitchen style cabinet at a right angle to the refrigerator -- facing where you walk between mud room and kitchen -- to store most cleaning products and any other non-kitchen items. This could be a cabinet that matches the kitchen cabinets in style and materials but is designed for storing specific items. At least the half near the refrigerator could have a counter top accessible from the kitchen. The base cabinet beneath it could be accessible from either the kitchen and/or the "hall" between the mudroom and kitchen.
You could still make the mudroom half of this cabinet a floor to ceiling cabinet and/or you could still create a tall open broom closet (with the kitchen wall as the back wall, between the powder room and the cleaning product cabinet) for your tall items -- broom, mop, vac, irning board. Across from that broom closet, between the powder room and the exterior door against the exterior/garage wall, you could put your bench, hatrack, coat rack.
If your refrigerator is, as it appears, going to be a single rather than double door, you need at least one countertop beside your refrigerator.located on the side opposite the refrigerator door hinge. You want to be able to lift items out of the fridge and set them on the countertop -- especially if you're moving items around to reach something in the back of the fridge. The kitchen side of your modified kitchen style cabinet for your cleaning products could be used for that purpose in addition to being a charging station for cell phones..
Personally hate "dead" corners -- those hard to reach base cabinet places beneath a corner countertop. they're only good for storing stuff rarely used. Not a fan of the turntables -- stuff inevitably falls off. You might want to consider corner drawers for your base cabinet in the other side of your kitchen near the sink. Did see a kitchen (Houzz site) a while back that had corner drawers beneath a countertop corner -- still likely had some "wasted space" on each side of the drawers unless the adjoining cabinet shelves were designed specifically to use that space.
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