Some dim outfit makes the floats.
I wondered about that as well. Going back almost a hundred years, floats for US military floatplanes were made by a company called EDO. They were based in NY, near various east coast aircraft manufacturers (Grumman, Martin, Vought, Curtis, etc.) that built seaplanes. They continued making floats after the military got out of the seaplane business, but eventually got swallowed up in the aerospace industry mergers post Cold War. When I first saw that article a few weeks ago, I tried to find out if, under new ownership, they were still in the float business. I had no luck.
There are a handful of float manufacturers in the US, but they are primarily involved in light/civil aviation. Lockheed, as a company, has no experience in the design, manufacture, and test of floats, so I would guess they would try to form at least an associate with some company with that experience.