@red3 I would encourage you to get some more surgical opinions as you may be offered different procedures. There are also some pelvis alignment disorders that are physical, and can mimic a lumbar spine problem and cause sciatic pain. If your imaging indicates a structural spine problem, physical therapy won't change that, but you could have a misalignment of your pelvis and muscles adding to symptoms and putting pressure on your spine. Research any surgeon you are considering because surgery can make you worse, and all spine surgeons are not equal. Some are excellent, and others are not. Make sure that this is the only type of surgery they do so they will be more experienced with spine issues. Read their research papers, and success rates for the procedure, as well as the success rate of the hospital of institution. I had cervical spine surgery at Mayo, and a great recovery and would highly recommend my neurosurgeon who is a spine deformity and cervical expert with spine orthopedic fellowship training too, and who does artificial discs and fusions. The lower end of the spine bears all the body weight, and any twisting or bending can put pressure on hardware like rods and screws that are used in spine surgeries. The screws can pull out if not placed correctly and held in place by good quality bone. There are also issues for smokers and healing from spine surgery, and many surgeons make a patient quit smoking before they operate. Smoking can cause a fusion to fail as a non-union. There are pros and cons to both fusion and disc replacement and some surgeons prefer one over the other. They are trained by the companies who make the hardware, so it's good to ask why a particular hardware or implant is recommended and if there are any other options to consider. You might want to get an opinion from a surgeon who does both. Here is a patient story about my Mayo surgeon and another patient with a lower spine issue that may be helpful. There is also a link about Lumbar Plexus Compression Syndrome written for physical therapists that explains the pelvis misaligmnent issues.
https://www.mayoclinic.org/biographies/fogelson-jeremy-l-m-d/bio-20055624
https://sharing.mayoclinic.org/2017/07/26/spinal-surgery-saves-teen-swimmers-mobility/?utm_campaign=search
https://sharing.mayoclinic.org/2019/01/09/using-the-art-of-medicine-to-overcome-fear-of-surgery/
Lumbar plexus Compression https://trainingandrehabilitation.com/identify-treat-lumbar-plexus-compression-syndrome-lpcs/