Did Snowden lose his citizenship? No. The US cannot revoke his citizenship per its laws. He fled to Russia and took an oath of citizenship there in 2022. But he didn’t renounce his US citizenship either.
Say someone says drink the cup of wiper fluid or I will shoot you, so you drink the wiper fluid. In a literal sense, you chose to drink the wiper fluid. I think most people would understand that you were forced to drink the wiper fluid.
Yea that might be it. But that doesn't strike me as unusual either. There are many situations where a criminal charged with a lot less has to surrender documents as a condition of being allowed out on bail while they await trial, if they're considered a flight risk. In Snowden's case, he knew he was going to face a lengthy criminal process and would be detained, so he (perhaps correctly) chose to leave before he made his revelations and before his movement was restricted.