Hi @8d88 - if by “viable” you mean “potentially game-winning at a high level of competitive play” then I believe the short answer is “no” and the long answer is “nope.” :)
Much longer and un-asked-for answer: It depends on your definition of “viable.” I like playing the US with a two-ocean strategy— particularly when I’m teaching the game—becuase it gives me the most control over the balance/fun ‘knobs’ of the game experience for the other players. If one player is dominating (or struggling), I can most effectively reach out and smack (or help) them with the US, and to do so requires two-ocean logistics (or some kind of “Green Skies” strat) to immediately get material where needed. My A1 purchase in these teaching games is definitely going to be two-ocean; enough carriers and transports to make up for any G1/J1 losses and to (lightly) defend and escort two oceans’ worth of shipping. My A2 purchase and moves will be more transports and escorts as needed, and the start of flowing material in whichever direction.
In many cases the two-ocean A1 purchase evolves into a normal one-ocean US strategy becuase it becomes quickly and painfully obvious which of the oceans is going to require the smacking (or helping) given dice, player skill, and other factors. This also depends on the kind and quantity of communication that is allowed/happening between the Allies.
While the two-ocean US strategy is mechanically very suboptimal for a dozen reasons which others here can explain better than me, the Allies will still often “win” teaching games where I play the US as a two-ocean power. In that regard, if winning = viable then I would say potentially yes—if you’re playing with new/poor players, particularly new/poor Axis players, and you want them to have a good time and come back next time—when you can crush them with an all-in Thorpe Thump, KGF, or whatever you like :)