Line a baking sheet with parchment paper. Pour a third of the melted dark chocolate onto prepared baking sheet and use an offset spatula to spread into an even layer, 1/8" thick.
Evenly sprinkle with half the pretzels, cherries, coconut, and pistachios.
Pour over remaining melted dark chocolate and spread to evenly cover ingredients.
Evenly sprinkle with remaining pretzels, cherries, coconut, and pistachios. Garnish with flaky sea salt.
Let bark cool until set, 1 hour, then break into pieces. Store bark in a resealable container until ready to eat.