A common mistake I see is developers often view a big and well known service and assume that means the entire market is fully catered to. For example, 'Firebase' is a large Google service that handles backend-as-a-service (BaaS). Does this mean the entire BaaS is now off the table for others?
Of course not! Maybe you can create a specialised BaaS that works great for the unique demands of Ruby developers, with a seamless SDK for them. There will be multiple specialised niches that Firebase does not cater to because they are so large that small niche areas are not worth their effort. But that niche might make a nice little lifestyle business for a developer! Do a good job of it and you become known as the go-to place for the Ruby community. (This is just an example, I have no idea if the Ruby community needs a Firebase BaaS)
On this note, without mentioning names, I'm going to share two real world examples of people I know turning businesses into profitable side projects in very very crowded markets.
One is so profitable in fact that the side project is about to become his full time business. He built a tool to do link tracking using social media pixels. I mean that's a suuuuuper crowded market, but he fine tuned it enough to serve a particular customer base of small to medium businesses and with a primary focus on managing retargeting pixels in one place.
The second business I know of was built in the market of checking cron job success/uptime and doing alerting on failures. Again, there are other products that do exactly this thing. But humans being humans don't connect purely with the feature sheet. From pricing to overall experience his product and customer service was different enough that people are paying for it. And while it was a slog to get his first 10 paying customers, his next 10 took only 1/3rd of the time that it did for the first 10.
This is just a supporting statement for the above comment. Have courage in yourself. Go forth! :)
Of course not! Maybe you can create a specialised BaaS that works great for the unique demands of Ruby developers, with a seamless SDK for them. There will be multiple specialised niches that Firebase does not cater to because they are so large that small niche areas are not worth their effort. But that niche might make a nice little lifestyle business for a developer! Do a good job of it and you become known as the go-to place for the Ruby community. (This is just an example, I have no idea if the Ruby community needs a Firebase BaaS)