If you want to reference the originals in Lightroom without exporting / importing, the easiest way is to add the Photos master folder to Lightroom as a folder:
1) open your pictures folder in finder, right click on the Photos library and select "View Package Contents". Keep this window open
2) In Lightroom, select the add folder option
3) Drag the Masters folder from the finder window opened in 1) onto the selection window that pops up in step 2)
This will then add the masters folder to lightroom and all your Photos pictures will appear in Lightroom
Be aware that if you have optimise storage on for your photos library, they may get removed from the disk at any time so it's best to use the "download originals" option in Photos
Also, you'll need to resync the folder in Lightroom whenever new pictures are added to Photos to see the changes in Lightroom