Here is the full list of all 22 Devolverland Expo achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Collect all the hidden pieces for the third unannounced game
Collect all the hidden pieces for the second unannounced game
Collect all the hidden pieces for the first unannounced game
Don't get caught by those frickin' laser beams
Defeat the Boss
Check out all the Devolver game booths
Watch all the trailers!
Watch the Shadow Warrior 3 trailer
Watch the Fall Guys trailer
Knock over all the walking Fall Guys
Watch the Serious Sam 4 trailer
Watch the Olija trailer
Watch the Blightbound trailer
Dare to don the Glove of Power (mkII)
Break the code to the ventilation system
Watch the Weird West trailer
Watch the Carrion trailer
Pick up an access pass for the expo
Take out a security drone
Unlock the door up to Security
Pick up your essential T-shirt launcher
Rewire the electrics to get in