As an E-commerce professional, what was your buying process like with creating a headless e-commerce store?

Hi – my girlfriend is applying for a job as a sales person at a headless e-commerce company (she doesn’t have a Reddit account). She believes it’s the future, but is concerned about the sales process because it isn’t the easiest concept to research or understand. For anyone who has purchased a headless e-commerce solution, would you mind sharing your evaluation criteria and thought process behind the solution you selected?