Figuring Out Target Market

Hi everyone! If it's okay, I would be grateful if we could get some feedback on how to determine a good target market for our product - Spade. I think my question applies to many tools that have a broad consumer market. Spade's a chrome extension that allows you to create, save, download, and share annotations across the web (https://spade.tools). We're planning to launch Spade for the second time as we have pivoted away from it being a research tool to a more general use case. Here are the use cases we've figured out so far: Professional: Giving feedback on a research paper / design / websites, annotating articles, and sharing ideas on them with teams. Students: Do homework on pdfs, drawing out hard problems and crossing out online quiz answers, noting down notes as you go on a website or a video, annotating articles for research Teachers: Marking up a presentation, sharing thoughts on work / texts with other teachers, grade and comment on essays, homework, reduce use of scanning by annotating directly on pdfs General: Hopping on https://spade.tools/blank and using it as a whiteboard or mindmap, making a purchase or decision between online selections - jotting down thoughts on each option How do you think we could narrow it down? Thanks so much for your help!