I’m not sure of the history, but I think Parkhamov was the guy who replicated Rossi’s effect just by reading what Rossi wrote. Since Rossi isn’t really a scientist submitting his findings for peer review but more of a tinkerer trying to become a trillionaire, that is a bit like learning magic from watching a magician.
https://www.lenr-forum.com/forum/thread/1199-ugo-abundo-parkhomov-replications/
When I was little I used to make aluminum and sodium hydroxide hydrogen/heat generators.
It cost very little money, and it worked very well for filling up balloons which you could then light on fire and study the hindenburg effect.
Nothing wrong with tinkerers.
The Wright brothers were tinkerers.
Edison was a tinkerer.
Yoshiro Nakamatsu is a tinkerer with a Phd................