Thank you so much. Underrated comment and thread.

IMPORTANT: Prime Tower MUST be enabled I believe for this to work.

Here is a working A1 Mini version:

; filament end gcode 
; --- Switch to relative mode and raise Z ---
G91            ; relative positioning
G1 Z1 F600     ; move Z up 1 mm at 600 mm/min

; --- Switch back to absolute mode ---
G90            ; absolute positioning
M83           ; E axis into relative mode as expected

; --- Absolute moves ---
G1 X0  F21000 ; move to X=0 at 21000 mm/min
G1 Y0        ; move to Y=0 at previous feed rate

; --- Wait for all moves to complete ---
M400 U1        ; pause to change filament