I have a P1S without an AMS.
I often do two-colour prints with text or a graphic on top, by pausing, changing filament with the printer’s screen, then resuming the print.
I think it may be impossible, but I’m hoping I might be able to put in one or more chunks of GCode that will allow me to change the filament twice (or more) on the same layer. Sort of like a manual-only AMS.
If that isn’t possible, I may try to see if I can find the end of a layer in the GCode to put in a pause so I can manually change it.