Yes—ready-made pinhole options do exist, usually as body-cap style accessories rather than conventional lenses. Community examples include Rising pinhole caps, Photojojo pinhole body caps for Canon and Nikon, and Skink pinhole/zone sieve products.

These products typically have a fixed effective focal length and very small aperture, and makers may provide approximate specs in the documentation. Because the distance from the pinhole to the sensor depends on the camera body, the effective focal length/aperture can vary slightly by mount or body.

However, they generally are not electronic lenses, so you should not expect aperture control or reliable EXIF aperture reporting unless a specific product says otherwise. In practice, most pinhole products are simple manual accessories made by specialty makers, not mainstream camera/lens manufacturers.