Regardless how Unity might transpile their applications, they must be combined with a LGPL library only after everything has been converted into binary object files, by the linker.

In order to comply with the LGPL requirement that the user must be able to rebuild the application after possibly modifying the LGPL library, the only thing that must be provided is the linker command line that creates the final static executable.

No other information about the proprietary source files or about how they are compiled needs to be provided.

If it is desired that no function names should be leaked from the proprietary code, everything except the LGPL libraries can be pre-linked into a big binary object file without information about the internal symbols, which can be linked with the LGPL libraries only as a final step for generating the statically-linked executable.

In this way, there is absolutely no difference in the information provided when static linking is used and when dynamic linking is used.

The claim that dynamic linking is necessary with LGPL libraries is completely wrong, because linking them statically, but only after linking the other libraries, is completely equivalent.