Ionide + vscode-solution-explorer
Ionide is a wonderful editor for F# and vscode-solution-explorer is a featureful tree view for .NET solutions and projects. This extension installs both with a bit of configuration to turn off the default Ionide tree view.
Yes, I know that Ionide includes a tree view for solutions and projects, but vscode-solution-explorer supports more features like
Turning the Ionide Tree View On Or Off
If you decide that you want both the Ionide tree view and the vscode-solution-explorer view then you can
easily turn the ionide view back on. The configuration setting ID is
Likewise, if the Ionide explorer is still showing for some reason (perhaps the setting was set somewhere else)