The worry I have regarding getting the wording of this just right is due to how Extra Attack is worded in the class features, and trying to translate it across into the intent of what I want out of this feat.
Effect: The effects of Extra Attack apply to attacks made as a bonus action.
For most classes, the wording JBPuffin suggests would work as bonus attacks are granted as a single strike and the Extra Attack wording works as intended in bumping it up to 2.
The exception is with Monks. Martial arts grants one strike, so the wording works in bumping it up to two. BUT Flurry of Blows specifies two strikes and Extra Attacks specifies two, meaning as written; spending Ki on Flurry of Blows is identical to not spending Ki and still making the same number of attacks.