Supplements advice, please!

I have never actually tried supplements for my Long Covid and I know I should talk to my doctor about this first (which I will) I just wanna get some advice and experiences from users here. I also know that not everything works for anyone here and the people that did find a working supplement dont come here as often either. I just want raw and reasonable advice and help, as I never actually took supplements in my life and Im getting my first paycheck soon which Im excited about. To shortly describe my Long Covid I dont have any neurological problems besides brain fog when I overexert myself but other than that its mostly POTS like symptoms, orthostatic intolerance and exercise intolerance. Very often fatigued and tired, adrenaline dumps (which are treated by low dose beta blockers) and slight muscle weakness/soreness. I get to do stuff around the house (thank god) and work for very few hours a week which are honestly only possible with my beta blockers.

Now to the supplement part; most things Ive read on here are about: Citrulline Malate Magnesium Malate together with Vitamin B1 (Thiamine) MCT powder Nattokinase Coq10

Now I'd guess getting all of them and just trying it around would be stupid and a waste of money but Im also not sure what to actually try and what could actually benefit me. Is it really just trial and error?