I worked at US Department of Treasury full-time
Amazing mission driven culture; great people.
Literally no downsides at all.
I applied online. The process took 4+ months. I interviewed at US Department of Treasury.
It is lengthy. I can take anywhere from 3 to 9 months to get onboard. Starts with a phone screening, then you come in for a panel interview, then you do a one on one and then you are notified on your selection.