So effectively they issue the securities themselves but the assets are considered bankruptcy remote and are not general corporate obligations. Further, it doesn't appear that the securities are considered government obligations, thus, any ED foreclosure wouldn't be considered ED from the government. I am not a lawyer and still not 100% familiar with agency CMOs but I am familiar with foreclosure of ABS collateral.
I know well about who gets the proceeds. I manage the credit and research for consumer and commercial ABS for PMs of a very large money manager.
The legal owner remains FNMA, the only people the city see are FNMA as the legal owner. So any ED would be considered ED from the government. FNMA has stated this already when cities were planning this, and cities agreed this is true. This is not in dispute by party of relevance.