Hi, if you import the ProBas or ProBas+ database from Nexus, you have the database in openLCA. Gemis data content is a large part of ProBas. ProBas is a bit stalled though it seems (screenshot I took today from the official site).
If you can select a process provider, you have a supply chain for your product (at least, one process providing the product, in the tab view you do not see how many processes are in this supply chain, but if you make a product system with autocomplete, you see this in the model graph - somehow, it is not terribly elegant as it is done now, a better version is in development).
Hope this helps!