I am a US citizen flying to Frankfurt tomorrow. I fly out of Frankfurt to Ulan Bator 20 hours later on a separately-purchased ticket, and have luggage I will need to pick up and re-check in Frankfurt. I just found out I count as "unvaccinated" due to only having single-dose J&J vaccine.

"Transit" is listed as an exceptional reason that allows an unvaccinated US citizen to enter Germany. But I don't see "transit" defined anywhere. Would my 20-hour, self-connecting layover, including passing customs, be allowed?