yep. thats as far as I got with the pineA64 I had here last year. my mate threw it at me thinking I might like it. I looked on the header for i2s and saw the voliumo chit chat, with a thread that kinda just dropped off with not much activity. I only saw the 2 i2s pins exposed ... somewhere ... and put it aside, but if what I read last night is right, the i2s in on a different header, not on the rpi2 legacy GPIO connector, its on the '2x17 pins "Euler" GPIO Header', but it does not have all the extra SDIO1-3 pins exposed for multichannel like the 2 x 11pin on the Rock64.
the LT in LTS is coming up in 2023, but that alone at least is comforting: ie. that they have such products where they commit to supply and support for 5 years.