are all albums photo stream items?
are all photos currently in any of my "albums" folders part of "photo stream?
MacBook Air 13″, macOS 13.4
No. Do you have a My Photo Stream album? it's only those photos and on Macs with MPS enabled they are already saved in the library. On an iPhone or iPad those that were not taken on that device should be saved to the device. Then you can disable MPS on all devices.
We now have 3 ways to get photos from a mobile device to our libraries on our Macs:
1 - activate iCloud Library and all transfers in either direction will be automatic.
2 - use AirDroop from the mobile device to the Mac and manually import into the Photos library.
3 - connect the mobile device to the Mac with it's USB charging cable, ope either Photos or Image Capture and import the desired photos into the library.