Zond spacecrafts
I'm reading Reginald Turnill's "The Moonlandings an eyewitness account" nd it's full of details and anecdotes of the early NASA space program.
For instance, Gemini 4 was not meant to achieve the first USA EVA. That was for Gemini 8. But Leonov had just spacewalked, so it was an early answer to it.
Before Apollo 1, there was a testing (meant for 1967) of the Apollo capsule and the LM sent both separately on Saturn 1B rockets. But the fire changed the plans.
Zond made a skip re-entry procedure, bouncing out of the atmosphere and this made the re-entry heat far les than a direct one like Apollo.
Etc...
Raoul