Beautiful. Minor feedback: rather than having a "use golang" directive, just allow imports of .go files. This is more idiomatic for JS bundlers.
replies(4):
Modern tools often make this tradeoff, like Astro, and none of the tools authors are claiming you need to use the tool.
Yes, the pattern can be abused, but dogmatic rules against mixing languages may also entail downsides.
To be clear I'm fine with importing .go from JS, it's the "go in file.js" thing I don't like.