This can be done. You'll want a digital camera with a moderate wide angle lens (just the zoom that comes with it is fine). Something like the Nikon D3400 is fine, will cost about $500.
Here is a link for basic information on stitched panoramas. The basics are conceptually simple, but the details get complicated: you would set the camera to manual exposure (manual everything, actually), tape down the zoom ring at a moderate wide angle, hold the camera vertically, and shoot 8 or 10 images of the scene, from left to right, overlapping by 50% or so with each image.
Then, you would take the photos into a software program and have it "stitch" them together to make a final single wide panoramic image. There are several programs that will work, PTGui is good and not too expensive at US$90. Lightroom and Photoshop can also do this, but they are more complex and more expensive.
As I said, the details get complicated, and quickly. You can shoot handheld (and maybe you have to, given the situation), though often a tripod is better, and a pano rotator makes the best final panos. But I would start handheld. You can shoot in-camera JPEG files, which can be used immediately, but later you might want to shoot raw files in camera and process them for the best initial image quality. (You should start by shooting both and using the JPEGs for now and keeping the raw files for later.) You'll want to nail down the proper exposure for the entire scene and lock it down manually, same with white balance and focus, so that the final blending of the images looks smooth.
Making large gallery prints is a giant rabbit hole you can dive into and never get out.
In my mind, your best bet is to find an expert printer with whom you can work on the final images together. You'll be able to figure out the best files to give the printer, and get test prints showing how they look before committing to a 4x7-foot canvas wrap.
Good luck.