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 the player-count line and rulebook that came with your copy; the format on this page is a practical two-player co-op setup that works well for a quick game night, a couple, or a remote call.