You can manually tag photos and identify people, though the UI flow is not the most convenient. (I've been trying it put for a couple months.)

How? I can’t find the option to add faces. I can add keywords and add labels but not faces

It isn't very intuitive, especially for one of the major features, but:

1. Select a photo with a recognizable face

2. Click the Pencil / Edit icon in the upper right menu

3. Select the People tab

4. Enter the name/names

Oh yea but if it doesn’t recognize a face then you can’t do anything. I have plenty of photos where the face is right there, but photoprism just didn’t recognize that there’s a face, and I can’t manually point at it and say “add a face, name it xxxx”