Any major risks with a combo of 300 mg of bupropion, 20 mg of escitalopram and adding 20 mg of omeprazole? risk of serotonin syndrome or seizure?

Theory yes Serotonin: Omeprazole is a MILD blocker of liver metabolism (and 20 is low dose). Those are average doses of two antidepressants. They have a WIDE margin of safety. So, serotonin syndrome (two antidepressants both raising serotonin) or seizures (too much welbutin) is a conceivable concern. But it sure isn't likely. Unless there's something else to cause seizures or other serotonin drugs.