Unfortunately, since there are relatively few turbo kits made for the Slingshot, chances are slim that any parts are interchangeable among the various kits. Also, Alpha's unique approach regarding relocating the TB also exacerbates the problem of interchangeability.
Things like the tune or exhaust can be addressed by existing vendors. With luck, a vendor might step forward willing to fab some parts as needed. Failing that, it would probably be a good idea t\for Alpha Turbo owners to group together and document as closely as possible the dimension of the various rube parts just in case. In all likelihood, barring an accident, the tubing is unlikely to ever really need replacing.
I think it would be good for Alpha to release as much as possible of their IP to the public, assuming they don't sell their IP as part of the business dissolution process. Such a move could go a long way toward ensuring support for former Alpha customers.