According to own U-Precision they send 85 dual wafer stage prototypes
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The technologies developed in the DWSi is not just for immersion but also EUV, because is maglev, they are aiming to less than 2.0 nm matching precision I guess closer to ASML. That and the research for advanced grating measuring devices was done also 2021.
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Their goal for now is to have a domestic immersion tool that can allow a 28nm process with reasonable performance. Any bottleneck is going to be, is in the process of or already has been solved.