Some avenues to consider/investigate (consult with your doctor before trying any treatment, but expect to hear "there's no reason to believe that will work" in many cases):

FLCCC I-RECOVER protocol: https://covid19criticalcare.com/covid-19-protocols/i-recover...

"Could tiny blood clots cause Long COVID's puzzling symptoms?" (article reports some people have had success with anti-coagulant therapies, but be especially careful with those): https://www.nature.com/articles/d41586-022-02286-7

Theory of Long COVID as Mast Cell Activation Syndrome (from one of the physicians who pioneered use of fluvoxamine in treatment): https://twitter.com/farid__jalali/status/1315060197988036608

From personal anecdata, I took a PQQ/CoQ10/NAC combo supplement recommended by the local supplements store after both of my two infections, and have never had any long-term symptoms. NAC in particular seems to show up often in the various recovery protocols that are floating around.