C208 Pilot reported when ready to depart and entering the runway they observed another aircraft opposite direction approximately 25 feet above them.

Narrative

My crew and I; were conducting regularly scheduled passenger flight operations from ZZZ airport to ZZZ1 airport. We had conducted and completed all taxi phase checklists and made the appropriate radio call stating our intentions to depart the uncontrolled field from Runway XX with an expected right downwind departure to the southeast. We then conducted our 'Take off checklist' without beginning any movement or crossing the hold short boundary into the runway environment; this took us approximately 30 seconds. We both listened and searched both approach ends for traffic. At no point between start up; turning our avionics on; taxi; and crossing the hold short boundary did we hear any radio call on the local CTAF for the area; discerning any inbound or outbound traffic. Almost immediately after our nose crossed the hold short boundary; my copilot and I saw; heard; and acknowledged traffic flying towards us approximately 25' above from the direction of Runway XY. After the incident we queried the pilot of the conflict aircraft and asked if he made a radio call; he said he did however just a 6 mile inbound call. After the incident; both my copilot and wondered how we could have missed him both verbally or visually; it was concluded the pilot of the conflict aircraft did not make anymore position reports and when we entered the runway environment his aircraft must have been in our high wing blind spot.