If I finish the game early, will I have to start a whole new game?

I've reached a point in the story where I'm given the choice to finish the game far earlier than its intended end.

While I haven't played Far Cry 4 or 5, I've heard that Far Cry 4 has a secret ending that skips the overwhelming majority of the actual game. I figured that Far Cry 6 might do something similar, and stumbled upon this piece of information on Wikipedia:

A secret ending can be found at the beginning of the game.

Rather than fight for Libertad, Dani escapes Yara through a boat given by Clara.

I believe I might have reached that very point in the story. However, I did spend 6 hours to get there, and would like to avoid losing them.

Normally, I'd just take this ending, then load my previous save and keep playing the rest of the game. But this game doesn't offer a "Save" option (it saves automatically), and there is no "Load" option either, only "Continue".

I'm concerned that by ending the story early, I might need to start a new game once more (and replay the first 6 hours), because the game will have automatically saved past a "Point Of No Return".

If I choose to see the secret ending, will I be able to return to a point just before I made that decision?

I have triggered this "ending" by going out of bounds in a boat much later in the game.

There's a short cutscene showing Dani on a beach listening to a news report saying the revolution was ended by Castillo, then the credits are shown. Then the game just goes on like nothing happened.

It's only a joke, not a secret ending.