This is now possible with sparse-checkout and symbolic links. For more details on how this works, please check out this gist

https://gist.github.com/ZhuoyunZhong/2c08c8549616e03b7f508fea64130558

The general idea is that you first add the submodule, then set up sparse-checkout in the submodule to track only the folders or files you need. Then you could use symbolic links to "place" the folder wherever you want.