Advice for multiplatform app

I have an idea for a multiplatform application that should run on Android and desktop systems and it should use either a CSV file or a sqlite database for persistence under the hood. Flutter looks like a promising framework to use as it can build for multiple platforms starting from a single codebase and it also directly supports Firebase, which may come in handy for authentication purposes, however, I've seen that Firebase authentication is not supported for desktop environments. Is there any workaround that could allow me to use it in this use case or should I resort to other methodologies?

Another option would be to develop two distinct applications, one for desktop environments and the other for Android, but the authentication remains a problem