There is indeed an Instrument Foreign Pilot (IFP) test. The knowledge base is the same as the Instrument Rating Airplane test but there are only 50 rather than 60 questions.
You may find these helpful:
Instrument Rating Airplane (IRA) Sample Questions (faa.gov)
FAA Airman Knowledge Testing Matrix
Airman Knowledge Testing Supplement for Instrument Rating (faa.gov)
Last edited by DLT1939; 8th Sep 2021 at 21:20.