Before puberty can any form of pregnancy happen? What about ovarian extopic pregnancy, where sperm enters the ovaries?

You asked this question a few hours ago, someone gave a good answer, and the answer hasn't changed since then.

Please don't ask any more questions until you have finished reading
Campbell Biology, 7th edition or newer
completely. You need to read it from cover to cover.

**** off, NBA.

In theory, before puberty you're not fertile, so you can't get pregnant. I've never heard of ovarian extopic pregnancy, but it sounds impossible. And anyway you are not producing eggs before puberty, so again, it should be impossible to get pregnant.