RolepaperIf the employer’s form makes the letter optional, spend the time on the CV. If they ask for one, three short paragraphs beat a page of adjectives.
Paragraph one: the product they ship, in their words. Paragraph two: one thing you shipped that maps to it. Paragraph three: timezone and start date.
Do not mention this aggregator. They do not care. Do not mention Indeed either. Brand-navigational cover letters read as spam.