Yes, you can play Wavelength with 2 players. The cleanest format is cooperative: one player becomes the Psychic, gives one clue, and stays quiet while the other player places the needle. Reveal the target, record the shared score, and switch roles for the next turn. This keeps both people involved without pretending that a two-person game has the same debate energy as a full party.
The official Wavelength App FAQ lists 2–10 players and describes the app as fully cooperative. For a physical edition, check your rulebook; this page gives a practical two-player co-op setup for a quick game night, a couple, or a remote call.