I'm sorry for your troubles. Living with pain sucks the life out of you.
I have had sciatic pain, but not that severe. It would hurt, but the biggest problem was if I coughed or sneezed my left leg went limp. If I felt a sneeze coming on I would have to drop to my knees or grab something to hold me up. I had other pain, but from the same cause. Which is weakening core muscles that let your spine pinch your spinal cord. It's been a long haul, but strengthening the muscles in the middle third of my body has helped me tremendously.
Stretches, a cortisone shot, and body core strengthening have worked miracles.
I've been to PT twice and the stretches on this web site cover most of what I was taught there. It works, but it takes time.
https://www.silversneakers.com/blog/sciatica-stretches-exercises-ease-pain-seniors/