I tend to get a tiny blob at the very last coordinate of the print. I wondering if there is anyway to get the nozzle to wipe and retract only on the last layer to smooth this blob out.
In cura, I dont believe , in prusaslicer you can put a custom GCode before the last layer, just add it there
It's the same in Cura. The Ending Gcode for many Creality printers include a wipe.
This is a partial snippet of the Ender 3 Pro Ending Gcode and it shows the "wipe" move as well as the "Present Print". It may need to be altered a bit for some printers (like Flash Forge), but mostly this will work if put in at the beginning of the "Ending G-Code" and before things start to shut down.
G91 ; Relative positioning
M83 ; Relative Extrusion
G1 F2700 E-2 ; Retract a bit
G1 F2700 E-2 Z0.2 ; Retract and raise Z
G0 F3000 X5 Y5 ; Wipe out
G0 Z10 ; Raise Z more
G90 ; Absolute positioning
M82 ; Absolute Extrusion
G0 F6000 X0 Y{machine_depth} ; Present print
But the ending gcode is after the last layer not before it
That wasn't clear.
You will have to custom "hand code" that. Once you move away from the Gcode toolpath you might need to add code that moves the nozzle back to the path. If "z-hops" are enabled then the nozzle might rise on a hop before you wipe.
You may be able to add something within the MESH:NONMESH section (the combing moves) of the layer prior to the last layer.
This is what the End GCode is for.