A solid BLS box would handle most emergencies until the proper help arrives. Airway adjuncts to maintain an open airway. NPA's and OPA's. NAR sells a collapsible BVM for ventilations. Various sized trauma pads, rolled gauze, 4x4's, Coban, Ace wraps, cavats. Izzy bandages, chest seals, TQ's, Saline wash. Sam splints. Tape. BP cuff, stethoscope, pen light, glucometer, gloves, shears, and maybe a cheapy pulse ox.
Cheat cards can be laminated and placed in the box. Ranges for vitals, Blood Sugar, FAST score, GCS.