I like the ease of cloud back up and was wondering if this scenario would work:
Can I NOT do a migration of my current photos and just continue uploading my new photos to Apple Photos so I have cloud back up. Then just pick and choose which photos I'd like to post process by copying and pasting selected photos from Apple Photos to my external hard drive? I would have Internal lightroom catalog storage and external image storage
It will help us to answer your question if you could provide the exact version number you have installed and details of your operating system e.g. • Windows 10 v1809, v1903; MacOS Mojave (10.14) Catalina (10.15) • Lightroom v3.2; Lightroom Classic v9.2, Lightroom Mobile iOS v5.2, Lightroom Mobile Android v5.2 You can find this from your application menu: Help >> System Info
I've just downloaded the most current version of the Lightroom Photography package - Photoshop, LR Classic and LR cloud based. Trying to decide if classic or cloud would be best. Most likely LR Classic since I use my desktop 90% of the time. Operating system is MAC OS Catalina ver 10.15.3. - thank you!
Lightroom Classic would be your best bet. But you want to avoid referencing the same files both in the Apple Photos app and Lightroom Classic. I guess that is what you may mean by copy & paste from Photos. The simplest method is to export from Photos either as an unmodified file or as a file with the Apple settings already made in the Photos app. Then import those duplicate copies from your external drive into Lightroom Classic.
Lightroom is a cloud service, similar to Photos only better. Lightroom Classic is a different application that manages images on hard drives, not the cloud. Photos is an Apple product, and Lightroom is an Adobe product. They don't work well together becuase their cloud services don't talk to each other.
It's not clear what you are trying to accomplish, so I probably haven't answered your question, but hopefully I have provided a little clarity into what your options are.