I'm pretty sure in the main opening, that is actually piano layered in with the synths, not just synths alone
That's what I assumed as well but Howarth said he didn't believe a real piano was used and looking at photos of Pi West studio during the session there isn't one spotted so I don't think it is.
"Visible at the extreme left is the unusual Stephens 24-track two-inch machine, chosen partly because it was more portable than other alternatives at the time! The secondary Tascam 80-8 machine is in the rack just to the right of the TV monitor, with the Linn LM1 drum machine above. The synth rack to the right contains, from top, two ARP Avatars; an ARP Sequencer and Sequential Model 700 programmer; an ARP Quadra; and a Sequential Prophet 5."
-Alan Howarth