Dulles Airport (IAD), serving mostly longer-haul (including international) flights to/from the DC area, is another airport served by a "better-than-nothing," rail-to-bus connection:
Airport and Rail Access | WMATA.
Current scuttlebutt is that the Silver Line extension to Dulles will open in early 2022. Station will be above-ground, opposite the terminal, so not a weather- and barrier-free schlep. See
https://www.dullesmetro.com/silver-line-stations/dulles-airport1/. But at least it'll provide passengers and their wheeled luggage a nonstop ride to the inner VA suburbs and central DC. I've returned to Dulles on many international flights, and just cringed with embarrassment when fellow passengers from, y'know, civilized countries expected that there'd be a smooth way to take public transit into the nation's capital. Nah. They had to wait for a pokey and infrequent bus or rent a car.