My understanding of I2S especially for SACD playback is there is no industry standard hence some manufactures of I2S capable DACs built in some configurability of their I2S pinouts (in this case, I think HDMI). SACD DSD playback with I2S seems so complicated unless the DAC is from the same manufacturer as the SACD player ? I've asked Paul McGowan of PSAudio to do a video on this very topic for years now but has not materialized. Perhaps someday...
I do not know how well I2S works with PCM.