It sounds like you just want Intellij Ultimate. Fleet is explicitly aiming to be VS Code like while Ultimate is just regular Intellij with access to most language plug-ins.
It was disappointing to see, as I am really tired of running multiple IDEs to work on mixed language projects.
mixed language projects are the __norm__, not the exception. I get most often bitten by this when I have both C++ and Python IntelliJ projects configured in one tree, and it starts complaining about project name clashes.
complete waste of time, and i wish they would fix outstanding bugs, especially small cosmetic ones in the existing products, which have the lowest risk of regressions. case in point https://youtrack.jetbrains.com/issue/DBE-11296 ... which after three years elicted the response "We have no plans to implement this feature in the near future."