This is more of a comment on the stream tools API, but I think the interaction between the helpers is confusing; I think we should have ArrayStream support pipeThrough; or alternatively add a (required) arg to toStream like convertArrayStream so that it takes care of it internally.

In any case the toStream function docs need updating, since it's advertise to always return a ReadableStream

We don't want to use ArrayStreams here because in that case all of the data gets decompressed regardless of what happens after it, since ArrayStreams don't have backpressure support. Since we want to limit the output size of the stream afterwards (in a future PR), we want to use a real stream here.

You're right that the docs need updating, though.