What is the official ruling on timing/time limits for sideboarding between games?

Ruling: There is no official ruling in the tournament rules specifying how much time players have for sideboarding. The standard expectation is to apply normal slow play rules and use pacing modeled on other competitive TCGs (such as 1-3 minutes between games).

Nuances:

• In untimed final matches, judges may be more lenient about slow play enforcement during sideboarding