There are two different RAW formats available. They are RAW and ProRAW.
RAW (also called Bayer RAW) is traditional RAW format that aims to represent what camera sensor has recorded without any image enhancing processing.
ProRAW is an Apple processed image format with uncompressed data (compression may be applied but Silver B&W Camera does not). It is a combination of RAW format and computational photography of the Apple devices.
RAW is photo format where data from digital cameras sensor is saved without extensive processing. Normal JPEG (or HEIC) photo is color temperature adjusted, noise cancelled, sharpened, cropped, compressed and possibly even more processed.
RAW is what the camera sensor sees. RAW file contains information about the shooting conditions so RAW photo editors can make first attempt to create good looking photo based on that. But you have freedom to use your photo editor tools to create the photo you desire as RAW file has more original information than JPEG can have.
RAW file shot with Silver B&W Camera is always a full color version of the photo. Any black and white conversion settings you applied when shooting where used to create the JPEG file. But the RAW version is the original full color data from camera sensor.
ProRAW is processed high quality image. Compared to a JPEG version created by iPhone the ProRAW image is less processed but compared to RAW (Bayer RAW) it is heavily processed.
ProRAW images contain lots of original data from camera sensor so it is suitable and actually intended for post processing with RAW photo editing software.
On iOS devices ProRAW lacks most of the limitations Bayer RAW has so it is much more easy to use. ProRAW is available on iPhone pro models starting 12 pro and 12 pro max (see Apple product details for specific device and OS version support).
RAW and ProRAW format is saved as .dng file combined in JPEG format .jpg file (or HEIF format .heic file). Your devices photo gallery shows the .jpg or .heic image but if you have RAW capable photo editor it can access the RAW data from .dng file.
On Mac computers Photos application can be used to export the photo to a separate .jpg (or .heic) and .dng files.
See this tutorial video how to access RAW or ProRAW photos here on YouTube.
RAW files are usually much larger than JPEG files. JPEG photo of 2 MB can easily be RAW file of 12 MB or more and in ProRAW with iPhone 12 pro or iPhone 13 pro about 25 MB.
When using RAW mode some camera functions are limited. These limitations are imposed by underlying hardware and operating system limitations and some are natural to RAW format.