Comparing my eight-year-old son’s goody bag to the one you are making for your nephew. Mostly similar with just a few exceptions. Some items you already mentioned you wouldn't include like the fire building items. I can understand that and realize I have a slight advantage being a parent rather than uncle. Anyway, FWIW, here's my son's list (SO FAR).

MEDICAL/FAK: Nothing fancy here, just a basic small pocket size kit from wally world. There is also a small bottle of hand sanitizer, a tube of lotion and assorted chapsticks.

SHELTER: Assorted space blankets; heatsheets blanket and bivvy (the basic one, not the 2.0); bright orange nylon poncho.

WARMTH/FIRE/HEAT: Assorted fire making items including strike anywhere matches in a waterproof case, red bic lighter, magnesium and flint bar, spark lite, tinder quik, cotton balls, small thin cardboard, fire starter material and a candle. Also included some hand warmers.

WATER: 1 Qt Canteen with metal cup, coffee filters, purification tablets, and recently added an oven bag.

SIGNALING/COMMUNICATIONS: Whistle and 2" x 3" Signal Mirror (both from PSP as is the spark lite and tinder quik above), plain red bandana.

FOOD: Assorted candy and cereal bars; packets of instant soup; stainless steel mess kit; lexan fork, spoon and knife; fishing kit (includes kit from PSP and additional kit from home supplies with a bobbin of 30 lb test spiderwire); assorted wire (the one from the PSP plus some craft wire and a spool of surplus trip wire).

TOOLS: Swiss army knife; CRKT M16-01Z (a small folding linerlock design) with auto LAWKS mechanism; Cold Steel SRK; Sharpener; Folding saw; wire saw; 2-AA cell LED mag-lite, Doug Ritter version of eQ headlamp.

MULTI-PURPOSE AND REPAIR: 100 ft Paracord; memo pad and pencil; duct tape (from PSP plus a roll of orange tape); aluminum foil (also from PSP); sewing kit; assorted magnifying lenses; safety pins; rubber bands

PERSONAL PROTECTION AND COMFORT: sunglasses; sunscreen in FAK; wet ones; boonie hat.

NAVIGATION: Button compass from PSP, clear base map compass, local area maps added as needed (I really struggle with including navigation items as I really just want DS to STAY PUT but adding these items implies it is ok for him to try self-rescue – better to have them than not is my only reason right now for including them).

MISCELLANEOUS: Back pack; his favorite small toy; family photo; binoculars; knot guide; kids survival primer (stay put, hug a tree, etc); any other items from the PSP I forgot to mention.

I have stuff missing I know, like extra batteries and large Ziplocs to store the stuff in. It’s a work in progress. I need to add the items you have that I/DS am/are missing (like Ziploc bags, field guides, towel, washrag, and so on)