Neuropathy with back pain exercise

I am 73 and haven't been diagnosed with any kind of PN yet, although, through extensive research, determined that I have some form of PN in my feet. I have a conductive nerve test in June (first available). Experiencing numbness in toes and balls of both feet moving to ankles, that causes balance issues. No falls as of yet. To exacerbate this, I suffer from spinal stenosis at my L4/5 and S1. I've had a radio frequency ablation that failed and just had an epidural.

Enough about my symptoms.

I've only been able to bear standing no longer than 10 or 15 minutes without having to sit to relieve the back pain, so exercise has been out of the question for me. About a year and a half ago I bought a treadmill that just sits there because I just can't use it for much more than 5 minutes due to my back pain. My granddaughters get more out of it when they come to visit!

So, finally my question.

What is a good indoors exercise machine I can use to get back into some halfway decent shape? Get the legs strengthened and burn some calories. I used to have a recumbant, but found I just didn't care for it and sold it. I'm thinking an old fashioned stationary bike would be best. Good for legs and burning calories and easy on the back. Any other ideas that I can't think of would be greatly appreciated!