I think it was all of them together, I basically tried to go all-in as my previous partial attempts never turned into stable improvements. I don't think without rowing machine I would get better as I wouldn't improve my blood flow, but the exercise alone didn't lead anywhere before (I tried it for 3 months a year before that).

I had somewhat of a similar experience treating a different condition I had. I wanted to take the scientific approach of taking one supplement at a time and measuring my response, but I ended up taking everything at once, and that worked wonders. But I'm still not sure if it was one specific thing that did 90% of the heavy lifting or if each one did 5%.

Read this, the doctor had only success if he combined multiple things together and has lab data showing no effect when either of them was taken separately:

https://xdrx.substack.com/p/how-i-recovered-from-long-covid-...

This could help your scientific brain a bit ;-)