I’m O negative - universal donor. I think you may be onto something connecting blood type and symptoms. I got it in early 2020, and have been a long hauler since. My initial infection was confusion and memory loss, followed 2 weeks later by fatigue that lasted a month, then nerve pain. I never got lung issues. My long haul issues for the past 3 years were memory and lack of appetite. Then a few weeks ago I had a seizure and have been diagnosed as epileptic. Covid is no joke.