I’m impressed by your resourcefulness to achieve what you have! However I’m pretty sure the procedural displacement isn’t limited to the pure normal direction like the displacement modifier is. If you take a look at the desert plane that starts perfectly flat, the procedural displacement pushes the geometry in a diagonal direction which makes for a “sharper detailed” version:

Therefore I don’t believe there’s a way to make a 100% accurate conversion from procedural displacement to geometry. Definitely a bummer. Something I hope the add soon.