Photos in Finder & App, Would Prefer Unified Location

An alternative solution...

If you are storing your photos also in Icloud - can you set up a shared album, and then copy a link to that (or to the individual images) and keep that in your project folder?

The Photos Library is managing the photos in its library package. This is not easily accessibly from the Finder. You can find the original image files, tat have been imported to Photos, but Photos 5 is renaming them and storing them in a way, that makes it hard to search for them ( How Photos 5.0 on Catalina Manages original Files and Filenames). The edited versions are equally hard to find. There is now easy way to access the Photos Library without using Photos or the Media Browser.

• To organise your Photos and work with the photos and adjust them use the Photos.app, as the Photos.app. Create albums and folders in Photos for each of your projects.
• To use the photos with other applications, use the Media Browser or the Photo browser of the particular application. usually the "file > Open" dialog in an application will show you a file chooser window. go to the Media section of the sidebar of the File Chooser window, click "Photos", then select the Photos library and click the tiny disclosure triangle to the left of Photos Library to reveal the albums.

It will look like this (sorry , my Mac is currently set to German). It may take a while to load, but you should be able to navigate the library like in Photos from within any application that supports the Media Browser.

However, in Photos 5 on Catalina versions you will only see JPEGs this way, not the HEIC images or RAW images. Problem in Photos 5 on Catalina: Grey Filenames in the Media Browser - Apple Community

In the earlier versions of Photos you could import photos to the Photos Library without copying them into the library. Photos would then just link to the items in the Finder ( referenced Photos Library). This is not as well supported as in professional applications. And it has annoying bus in Photos 5. I cannot recommend to use a referenced library in Photos 5 on Catalina - it is not worth the trouble and will create more problems than it will solve. (Disadvantages of a Referenced Library in Photos - Updated for macOS 10.15 Catalina)

A good idea, Tony, but the photos in a shared album are not having the same quality as the originals in the Photos Library. They are just good enough to show our photos off to friends and family, but they are downsized to 2048 pixels at the longest edge, and the titles, descriptions, keywords, dates , locations, original filenames are missing. Most of the work we invested into the photos will be lost, and it will not work for projects, where we need the original quality and the metadata.

Ah - OK. Thanks for info. I've a lot to learn here. (It's why I'm posting :-) )

Use a different application. One that can index your project folders and so show you the images in those, plus maintain - safely - an index of your photos. Check out OnOne Photo Raw for such and app.