In principle you can get the local file path from any folder and then save it e.g. in eLabFTW in the editor section. This would again work like a link, but eLabFTW is not a local application and therefore the file explorer is not opened directly (because currently addresses that are not web addresses are filtered out). Whenever needed, you can copy the saved address and paste it in the file explorer again and so indirectly create a connection. So it is enough to save the file path as text element in eLabFTW.