XBEE PRO 868 direct io

Since I can’t find any info about direct IO transmission (like S1 platform) I presume it’s not available?

Correct. It is not there. Only the 802.15.4 and some of the older 900Mhz units do that.

The newer units (ZigBee, DigiMesh, 868DP or 868DM) do not support it.