Diet and Nutrition, Kitchen Appliances, Cooking, Supplements, Vitamins,
Mattresses, CBD, Relationships + Dating, Survival + Doomsday Prep
Software: Email Platforms, Web Hosting, Funnel Programs, Virtually any software you can thing of.
Wealth: Make Money Online, Personal Finance + Credit Cards, Entrepreneurship, Business, Stocks, Real Estate, Investing, E-commerce
Electronics: Camera Gear, DSLRs, Lenses, Photography, Videography, Computers, Smartphones, Headphones, Drones, Gaming Accessories
Hobbies: Travel, Fishing, Outdoors, Music, Cars, Gaming, and much, MUCH more...
ANY niche can be made profitable and nobody is perfect with their first choice. It's more important to focus on just learning the fundamentals since it's easy to make a second or third business in a different niche.
PS. If you're having trouble choosing ONE specific niche, you can always make a general website/blog and focus on other niches in the future.