You might try this thread here. Which was started recently.
Golden Age Hero A-Z
https://comicbookplus.com/forum/index.php?topic=17761.0 A few Details on the ones in my list:-
Both versions of FunnyMan might have possibilities.
Grenade - only one appearance - A NaZI killed his brother with a grenade, so, yep, he went around killing NAZis with Grenades.
Impossible Man - If I remember correctly, the Golden Age version was born on a planet where everybody had superpowers, except him!
Kid Eternity - could bring back any historical person to fight or solve a problem for him. Now a DC Character, but you could use the idea under another name.
Phantasmo - let you find out that one by yourself.
Quicksilver - Marvel grabbed the name, DC brought him back as MAX MERCURY
The Yama Lama of Ka-Bang - one appearance only - a sort Golden Age 'Ancient One'
Try this Database - Not all of these will be on this site, and there will be Heroes on this site that are non--USA characters that are not on this list.
https://pdsh.fandom.com/wiki/Public_Domain_Super_Heroes