macOS 27’s Photos update includes full-resolution support for iCloud Shared Albums, according to the release overview. The same coverage says Windows and Android users can participate through iCloud.com, making it easier to share a collection with family members who are not all using Apple devices.
This is particularly useful when the recipient may want to crop, print, or edit a photograph. A lower-resolution shared copy can look fine on a phone but disappoint when printed or enlarged. Full-resolution delivery is a better default for photos that might become keepsakes.
Before replacing an existing sharing workflow, test with one original high-resolution image: upload it, download it from a second device or browser, and compare pixel dimensions and file size. Confirm which options are available on each device version.