The Nittany Lions will host an open practice from 7 to 9 p.m. on Saturday, August 12, at the Lasch Practice Fields.
Oregon and Washington will become the Big Ten's 17th and 18th teams.
Johnson hauled in 20 receptions for 328 yards and four touchdowns during the 2022 season.
Dufault is the first walk-on commitment of the Nittany Lions' recruiting Class of 2024.