How to force my MacBook scan for PEOPLE please?

Scanning more than 100000 photos may take more than a month.

Let your Mac Book run day and night. The message "0 photos scanned" may not be accurate. When my Mac has been running Monterey, Photos has not been updating the status messages continually. The count for scanned photos seemed to be stuck on "0" and jumped then to finished after more than a week.

Where is your large Photos Library stored? Are you keeping it in your Pictures folder on the internal drive or on an external volume? If you are using anexternalvolume, you may want to check if it is formatted correctly (Move your Photos library to save space on your Mac - Apple Support) . The drive needs a wired connection, not a network connection.

You may also want to check if all media files in your library are in a supported format. Videos or photos in a legacy format could cause the background processes to hang.

Try this, i.e. priming the pump:

1 - pick a few photos with a variety of people in them that you want to identify and open the full sized view.

2 - bring up the Info pane for that photo and click on the Add Faces button.

3 - place the circle over the person you want to have in the People view and enter their name.

4 - after doing that for a number of people put Photos in the background (do not close or sleep the Mac) and then check the photoanalysisd process in Activity Monitor to see if it's started scanning for faces.