If you're searching for something like this, take a look at threeshake which was made to generate svelthree-three. svelthree-three is an abandoned concept and will not be needed for svelthree!
This is a modified version of three.js for usage with svelthree. It's basically the original version where some modules have been moved from examples/jsm folder to src folder in order to make them treeshakable. Every time three.js updates to a new major version, a new svelthree-three version will also be created in a new branch. "Old" branches will not change, just bug fixed if needed.
It contains:
examples/jsmfolder: original three.js modules which have been moved to src and modifiedsrcfolder: three.js source including modified modules fromexamples/jsm