Sadly extreme exhaustion is part of Long COVID. To manage it, I take low dose naltrexone that helps me have deep sleep when I can sleep. I also limit my activity. I do no more than 20 minutes at a time. When I say activity, it could be washing dishes, doing laundry, cooking if I can stand the smell and actually crave food. The more you push, the more your body will fall apart. I tried pushing through this for a long time. I just ended up bedridden and miserable for days. It does really help to limit your activity. Good luck. I am sorry, you are going through this.