How do I achieve an oval crop of an image from Photos
This question was asked and answered in 2014, but the instructions no longer apply to Monterey - it could be done using Preview then, but apparently not now
You can do it with the Preview app. Export your photo to your desktop. Open it in Preview. In Preview, do View/Show Markup Toolbar. Choose the elliptical selection option. Drag select your oval shape onto the photo. Click on the Crop button in the upper right of the Preview screen. Save.
-- Rich