Companies are made up of people, and tech startups are mostly made up of developers. It's one of the building blocks of your project. When selecting a language to help solve a problem, it's important to consider not only how it will be used to build the solution, but also how it will be maintained in the medium and long term. Unfortunately, Ruby is showing signs that it may not be a long-term solution if you observe the "Learning to Code" chart tab on Stackoverflow.:
https://survey.stackoverflow.co/2022/#most-popular-technologies-language-learn
Hiring developers is already a difficult task, as the demand for developers is higher than the availability. If your company was built using a language for which the availability of developers is decreasing, it will become harder to grow or even maintain your codebase. Most Ruby developers on the market are already senior and working for established companies, and you will have to compete with companies like Github and Airbnb and many others. I'm afraid that in a far-off apocalyptic future, Ruby may become what COBOL is today: a language with many running legacy systems, but without developers to maintain them.
Typescript as an alternative
Considering maturity, toolchain, frameworks, and a growing developer community, Typescript (a compiled typed version of Javascript) can be a good alternative.
Python also has a growing community, but it is not as ubiquitous as JS and has a higher average salary and demand because it is used in many data science projects.
Although TypeScript does not have the maturity, elegance, and established web frameworks of Ruby (such as Ruby on Rails), it has a growing community and a production-ready ecosystem that seems to have a brighter future. It is still possible to create a Ruby-based startup today, but if you are aiming for a long-term solution, you should consider who will be maintaining and creating and implementing features in the foreseeable future.
StackOverflow and Google searches are unlikely to be good indicators. They represent what people are looking for, ignoring what causes people to search for answers. Perhaps rails, and ruby, just have great documentation while Typescript is more difficult to onboard on?