Legacy applications already on VFP are a good candidate. If you plan to move to iOS and Android apps, VFP is not for you. Also, in future access to VFP programmers may be limited. You could use VFP as a powerful database tool. I know of many programmers who love to exploit the features of VFP to create easy to use applications.
I always used and develop API with RapidAPI so also recommend to new people to use and learn about APIs. If we discuss about new user it's so easy to learn and develop API free of cost as well as paid subscription. My experience with RapidAPI is awesome.
Although MS has discontinued support of VFP there is a good community of programmers that are available for help. In fact we have several programmers at Apptread that are skilled not only in VFP but also .NET so that if there is a need to migrate some parts of applications to .NET , it is easy for us to do that.
We are only using FoxPro because it is the only way to add custom plugins into the software we use to manage our stock. FoxPro is a semi-oriented object language and should clearly not be compared with recent technologies.
Firebase is also good tools for user who are working on APIs but the marketplace of Rapid API is non comparative. Like how it's creates APIs and testing phase, supporting of multiple API types etc. These features makes Rapid API very unique from else ones.