How do I add a cross, (say + shape or x) as a graphic to a plot in a similar way as I would add a point using Point.

Existing solutions (https://mathematica.stackexchange.com/a/155162/45020) seem to always use a whole extra listplot. This seems cumbersome for just adding one point. 

Additionally I noticed that the two lines of the cross for some reason don't cross in the middle in that answer (most noticeable if you take FontSize -> 15).

So how do I add a + or - shape to a plot, centered at the point I give it and with the obvious required symmetries regardless of the size of the marker.

I would be hoping for something of the form `Show[plot,Graphics[cross[{x, y}]]]` with very similar behavior to Point but instead showing a cross.