Windows

Supported but

• UNC path is not supported

macOS

Supported

Linux

Supported

BSD

Not sure. While some BSD distribution does not support -maxdepth option on find command, you may need to overwrite g:fern#scheme#file#provider#impl manually like

let g:fern#scheme#file#provider#impl = 'ls'

let g:fern#scheme#file#provider#impl = 'readdir'

let g:fern#scheme#file#provider#impl = 'glob'

https://github.com/lambdalisue/fern.vim/issues/237#issuecomment-703719289