[azakai]

For current support, see

https://webassembly.org/features/

Chrome (and other Chromium-based browsers) and Firefox have had WasmGC enabled for a few releases now. But Safari doesn't yet last I heard.

Sheets can serve a JS version to browsers without WasmGC, since they can compile the same code to either JS or Wasm.

About Kotlin, I know they have a working WasmGC toolchain that works very well, so personally I think it is a good option in general. But I don't know offhand about current users or plans.