Suggestions from an army ranger:

https://www.amazon.com/Therm-Rest-Honcho-Wearable-Blanket/dp/B09LNYV9W4/ref=asc_df_B002OYD4EO/?tag=&linkCode=df0&hvadid=343181728959&hvpos=&hvnetw=g&hvrand=15874274723020840899&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9013898&hvtargid=pla-684266048121&psc=1&ref=&adgrpid=69473715019&th=1

https://www.amazon.com/Hazard-APR-PNVL-R-BLK-Poncho-Villa-Technical/dp/B00AJ5FQF0/ref=mp_s_a_1_10?crid=P0C1SSB40C4Z&keywords=white+goretex+poncho&qid=1662998866&sprefix=white+goretex+poncho%2Caps%2C183&sr=8-10

Good for hiding from FLIR. The second option is more affordable, and both are very lightweight and take up very little room in a suitcase, which would make them great affordable options for you to bring across the Atlantic.