Download Sieve.

Mac

macOS 14 or later, Apple silicon. Free and open source.

Open the disk image you downloaded.
Drag Sieve to Applications.
Open Sieve. macOS refuses to open it, because this build is not notarized by Apple.
Open System Settings, then Privacy & Security.
Scroll to the message about Sieve and choose Open Anyway.
Confirm. Sieve opens, and opens without asking from then on.

Sieve downloads its vision model once, 0.86 GB. After that it works offline.

Windows builds are on the GitHub releases page when available.

Unzip it, then add it in Lightroom Classic under File > Plug-in Manager > Add.