Thanks @brett for your response. I will try loading scenes asynchronously, which may solve the issue.
But honestly it seems like this is an issue that’s solvable by FMOD. It could create an iframe (or similar, like a seperate wasm environment) that does all the processing.
I’m pretty sure that if I had two Unity webgl builds running on the same page, scene loading in one wouldn’t halt music in the second. So if that’s the case, it’s technically possible for FMOD to handle this in the background, especially since it loads the banks from streamingassets.
Whether that is worth it or not is not up to me of course, but it seems to me that the industry standard for game audio should be able to play music without interruption. And if my proposed solution has side effects that I’m not thinking of, it could be made optional.