The pathfinding nodes get positioned to the nearest cell, so maybe what you could do is use your own movement system instead of pathfinding's in-built movement (eg. rexrainbow's MoveTo plugin), then have pathfinder create waypoints for each node. For the last waypoint, you'd ignore the final node & use mouse XY position (stored onButtonRelease when initially setting the path).
There might be a way to do this with Pathfinding, but the only useful things I can see are the 'Is moving along path' condition & the 'CurrentNode' expression (NodeCount-1 would give you the final node), & no way of setting NodeX/Yat.