2. Left Handed Hitting Outfielder
Putting this at the 2 spot leaves the obvious position for number 1, but the Nationals could use a Left Handed bat, particularly a power bat. They tried the Corey Dickerson route last season and it turned out poorly, but you can see the Nationals' desire to play matchups and platoon Left Field against Right-Handed and Left-Handed pitching matchups.
Stone Garrett will be back after a promising introduction to DC, and is a candidate to DH some for the Nationals given the current roster. So even if the Nationals went with a Right-Handed bat or a Left-Handed bat that proved serviceable against Left-Handed pitching, Garrett could still be a factor in the lineup.
Unfortunately, there are not a ton of great options in this regard. Cody Bellinger of course is available, but that does not seem remotely in the realm of possibilities for the Nationals. Joc Pederson also seems like a strong fit, but he, like 95% of the Free Agent class, is likely out of the Nationals' self-imposed price range. They need to find a Lefty and Power somewhere, so it would be great if they could find both in the same player. They just have to make the effort to do so.
Possible Fits: Joc Pederson, David Peralta, Joey Gallo