Are sideboards allowed in Riftbound, and if so, what are the rules for using them?

Ruling: Sideboards are allowed and must be either 0 or exactly 8 cards. You can swap cards between games in a match (not between tournament rounds).

Sequence:

• Game 1 must be played with your deck in its original configuration
• Between games in a match (e.g., between game 1 and game 2), you may sideboard
• You cannot change your deck between different rounds of a tournament (only between games within the same match against the same opponent)

Nuances:

• The sideboard size is restricted to exactly 0 or 8 cards (no other numbers allowed)