"Not dull, not stabbing, slightly tingly (used to be worse; the tingles have gotten better) but mainly fatigued.".... Also Alpha lipoid acid, Prickly Ash, St John’s wort
"...long COVID hospitalizations. " I doubt Wood betony would work here, it is for acuter muscular pain, not chronic . It sounds circulatory and I would try enhancing circulation to the legs (Ginger, Butchers Broom, Gotu Kola, Goji Berry, etc)
(1) no
(2) Compound Arnica oil may help