We already have a NeoVim plugin [0] that makes replacing Xcode somewhat possible. It's not perfect and requires that you have Xcode around for certain scenarios but I have been using it as my daily driver for the last month.
I think you would only need xcode-build-server [1] in order to get autocompletion in VSCode.
I think you would only need xcode-build-server [1] in order to get autocompletion in VSCode.
[0] https://github.com/wojciech-kulik/xcodebuild.nvim
[1] https://github.com/SolaWing/xcode-build-server