You can never move into a "Half Hex".
Reference Book Page 6
A unit cannot move into or through incomplete hexes along the
game board’s edges.
Advance could not be used if the defending unit does not or can not retreat from it's space (Unless eliminated) as you are required to move into the defending units original space.
Reference Book Page 2
After an attack eliminates an adjacent target unit or forces an
adjacent target unit to move from its original hex during combat,
the attacking unit may advance. To advance, the attacking unit
moves into the target unit’s original hex.
This would be the same when using pursue
Reference Book Page 7
The player must move the attacking unit into the hex the target
unit occupied before moving it any further.