I work with Firebase for six years, and during the time, I saw it transforming from a database as a service to an all-in-one platform for apps development and growth. Even though Firebase has plenty of services, it doesn't provide serviced backups for its data.
I liked the niche and decided to test the waters. I quickly created a landing using Carrd: https://backfire.store, created thread at Firebase Subreddit, posted ads on Google and Twitter. In total, I spent €50 and got six leads that I immediately started interviewing.