Kapitan Montag wrote:Can you summon units in turn 1 (either by Daemonic ritual or
GSC psychic powers)
They are not strategic reserves, but do they count as a reinforcement unit?
From p208 reinforcement unit: Unit starts the battle in a location other than the battlefield.
Summoned units don't exist at the start of the battle so do they get around the first battleground restriction?
Yes, you can summon turn 1, just like in 8th edition, for the exact reason you posted.