ownCloud integration - https://owncloud.org/
it is pretty self described
I am for - sharing folders in projects would be great, Google My Cloud doesn't work, because of sharing type, but OwnCloud or NextCloud are good options.
Nextcloud (the new fork of ownCloud) seems to be the better solution and is more future-proof. See this suggestion: https://freedcamp.uservoice.com/forums/126945-suggestions-for-features/suggestions/16033465-nextcloud-integration