Well I screwed up, slightly.
Yes we captured a declared route for AF1 to Warsaw. But the lat/long on the screencap was that of an RAF plane S of Ireland. The last capped lat/long for AF1 turns out to be about 30 mi. N of Venice.
It's very possible that AF1 was giving spurious locations on purpose.
Currently its radar signature has disappeared again (a rather common occurrence when monitoring a flight).
Continuing to monitor.
ADSB just showed a USAF plane with AF1-type markings in western Germany. (pic) Looks like it just took off and is gaining altitude. (pic2) So maybe they refuelled. Not showing a planned route at this time (most MIL planes don't declare their route on ADSB).
Godspeed POTUS et al.