Should I pluralize based on an item in parentheses [duplicate]

Which of the following two sentences is correct:

Jon (and Michael) is smart.
Jon (and Michael) are smart.

This example is clearly contrived but my question is whether the sentence should be grammatically correct when you erase the text in parentheses (Jon is smart) or should it be grammatically correct when read with the text in parentheses (Jon and Michael are smart).

Solution 1:

Note the use of is in this sentence: My friend (and her brother) is coming today. The subject is My friend. Despite appearances, parentheses are never part of the subject.

According to https://data.grammarbook.com/blog/commas/all-about-parentheses/