C208 pilot reported a NMAC that required evasive action be taken while on an instrument approach.

Narrative

I had the fortunate misfortune of experiencing a near miss today while on approach to ZZZ. I was on an instrument flight plan and flying the outer portion of the instrument approach; which I was cleared for by Center. Weather in the area was VMC; and I was flying easterly into the sun. An unknown; non-participant VFR aircraft wandered into the approach segment where I was located- co-altitude; opposite direction. I was made aware of this via a traffic advisory by the tower; and no cockpit instrumentation alerted me to the presence of another aircraft during the event. I acquired the aircraft visually on a forward quarter nose to nose collision course with less than a mile of separation. I arrested descent while adding power to take evasive action and pass clear of the other aircraft. I estimate the separation between aircraft when passing clear was approximately 100 feet. Had no action been taken; a mishap would have likely occurred. The other aircraft did not maneuver from what I could see. Since the event occurred well outside the FAF; and I still had positive navigation; I determined I was still within the constraints of my approach clearance. I elected to continue the approach and landed without further issue. I spoke with ZZZ tower on the phone after landing (this was not requested; I proactively called them- spoke with the controller who was working the tower at the time of the event) about the event and I believe they are also filing a near-miss report. They did not have 2 way comms with the other aircraft; which was outside their airspace anyway. This event highlights the importance of maintaining visual lookout on an IFR flight plan while in VMC; particularly during the approach/descent phases.