I'm still learning the rules for PF2 but it seems that Electric Arc meets all the criteria for Scintillating Spell metamagic (in bold):
Your spells become a radiant display of light and color. If your next action is to Cast a Spell that doesn't have the darkness trait, has no duration, and requires creatures to attempt a Reflex save, the spell explodes in a spray of scintillating lights, in addition to its other effects. Each creature that failed its Reflex save against the spell is dazzled for 1 round, and those who critically failed are instead blinded for 1 round.
Am I missing something?
Best Answer
Scintillating Spell Works With Cantrips
You haven't missed some hidden rule here, the only requirements are those quoted from the action:
Electric arc meets each of these requirements so it works with Scintillating Spell.
More broadly, any spell that meets those requirements also works with the metamagic feat, including focus spells, innate spells, or cantrips.