Just travelled out of the US to Japan for vacation end of May. ANA airline wouldn't let us put an expired green card in their site, so we added 4 years to the expiration date to match the extension letter.
Also applied for Global Entry beforehand on 1/24/24. My (USC) Global Entry was conditionally approved immediately, but SO was not - until he finally got conditionally approved during our vacation end of May.
When we arrived in US, we went to the Global Entry Enrollment On Arrival line instead of regular immigration. They just asked the typical Global Entry interview questions, have you committed any crimes, do you have any foreign citizenships. Took the extension letter no problem, and we were approved for Global Entry as well.