I have the beginnings of a myopathy problem. I have thought about taking Metformin to experiment but your post really turns me off that idea.
I can tell you that for my particular genetic make up a product from Life Extension makes a huge difference with fatigue and general well being.
I consider in the senolytic category
Still, not everybody has that reaction so it may or may not work for you. It's a drug you take in weekly steps, from 1 to 4, at least that's how it worked for me so you can start slow.
Personally, I'm doing whatever I have to, to never need anything like it ever again.