It should be possible to modify https://github.com/dotnet/icu/tree/maint/maint-67/icu-filters and generate the data file for only English instead of EFIGS to see how much space we save.

To generate the file, you need to build the full repo, and then you can rebuild the data files after adjusting the filter with make -f icu.mk data-icudt TARGET_OS=browser TARGET_ARCHITECTURE=wasm.