As You've probably noticed, this is a really deep rabbit hole to dive into. After WW2, there were a few pioneers that dove into this, researched it and then talked publicly about it during presentations and interviews. One of those pioneers was Jordan Maxwell. There are lots of videos with him explaining parts of these topics online. Because of censorship, You'll find the best ones on Rumble and Bitchute. Here's just one of them:

https://rumble.com/v2svq44-jordan-maxwell-hidden-history.html