I never knew how much I would need something... Buffered streaming of UTF-8 encoded bytes is OP.
https://encoding.matthewnelson.io/library/core/io.matthewnelson.encoding.core/-decoder/-companion/decode-buffered.html
https://encoding.matthewnelson.io/library/core/io.matthewnelson.encoding.core/-decoder/-companion/decode-buffered.html