Versailles targeted Germany's naval industrial memory

Could Germany join the Washington or London naval treaties if American goodwill allowed it to retain a credible military in the 1920s?

Only in a much more limited form, because Britain had deliberately dismantled the industrial and human foundations needed to rebuild a major German battle fleet.

British naval policy at Versailles was designed to make German fleet reconstruction difficult at every level, not merely to cap the number of surviving ships. Destroyed plant and tooling interrupted production, while the disappearance of viable careers prevented one generation of specialists from training the next. Skilled shipyard workers also emigrated, including to American yards, carrying expertise away from Germany. United States goodwill in the 1920s would not by itself persuade Britain to restore that capacity or admit Germany as an equal capital-ship power. Any limited cruiser settlement would invite British demands for separate dominion allocations, making it unattractive to Washington as well.