You can go around some of the extra processing by using other camera apps, for example "Open Camera". It can even shoot RAW photos, so that the least amount of processing is applied to the image. Unfortunately, you can't disable all of the processing, because some of it happen on the hardware, or in the camera's kernel module.
Sort of - (I assume for PR/marketing reasons) Apple doesn't let apps get access to actual raw sensor data. It may be possible to skip the steps that are causing the most trouble here.
Why don't you just try shooting it ProRAW, then try shooting a single shot RAW using a third-party app such as Halide? The latter option certainly removes any fancy computational photography from the pipeline.
https://opencamera.org.uk/