1) Can a grenade be thrown at an intersection if that intersection has concealment? (See the Vat Garden in the Starfinder Society Quest "Into the Unknown as an example encoutner). It seems that they do, so long as the character has Line of Effect.
2) If it can (as I assume), is there still a 20% miss chance on the throw if the target intersection has concealment? If so, I assume that it follows the rules for missing with a thrown weapon on page 245 if the % roll is 20 or less.