That's rather underselling it. If they have a proven, working, commercially viable design for a fusion power plant, they could probably just write a paper about how it works and collect their Nobel prize for physics next year.
Is anyone better versed in this? It seems strangely opaque for such a large-scale project.
They are taking very large calculated risks, attempting their first success, apparently with reason to believe it may work, in a market with enormous financial potential.
This a good period to shut-up and execute, and neither set themselves up to be a public debacle, or set up competition to arrive closer on their heals.
Then become a regular (but favored) customer, as the supply side becomes truly net profitable.
Even once they demonstrate fusion and viable levels of power extraction, it seems there would still be an issue of what is the level of "wear and tear" (incl. any radioactivity) of the fusion chamber - which it would seem may ultimately be a matter of try it for an extended period of time and see.