I guess I need to understand whether or not you want to keep using Photos.app or not. If you just want to regain access to the images that have been imported into that app you can simply move them into whatever spot you want.
Control-click on the "Photos Library.photoslibrary" item where ever you find it (In the apps prefs is a "Show in Finder" button just beneath the 'Library Location:' info). That button will open a Finder window and display the actual "folder" (which is not a 'normal' folder, of course). Now you can control-click and choose the "Show Package Contents" item. Your images are in a series of (real) date-based folders in the "Masters" folder. It would probably be best to make duplicates and move them to the chosen location. If you move the actual images, you will probably completely confuse the meager brain of the Photos.app!
If you don't want Photos.app to store/move your images, you might try unchecking the "Copy items to the Photos library" checkbox. I think that's what you have already done?
I've never used iPhotos, iTunes, Photos (btw, is that what you're referring to with "photos"?), etc. I still use Image Capture to get images off my camera. All go into my cleverly named "Pictures" folder. Once there, I create folders that I can then select in Lightroom for later cataloging (that's the major use of LR, other than editing, of course). You just have to remember that Apple (just like MS) wants to do things the way they want, and it is likely to change over the years... heather we users like it or not. That's the main reason I simply don't use lots of what Apple wants me to. I agree, you 'work flow' was created only because Apple forced it on you. That's the complete opposite of what used to make Apple apps so nice.
Lightroom is one a the few Adobe apps that is still downloadable, but I've found it does have some missing items compared to the CC subscription version. Still, it's not that expensive and works great with PS and most any other pixel based editors.
Why fight the computer that's supposed to be fun?!
