Learn Finnish: Mä oon tosi ylpeä, et sä et oo luovuttanu. - I am really proud that you haven't given up.

In spoken Finnish (puhekieli), it is very common to drop the final -t from past participles. The standard written form is luovuttanut (given up), but in everyday speech, it becomes luovuttanu. You will hear this happening with almost all verbs, like tehny instead of tehnyt or väsyny instead of väsynyt.

Why does the word et appear twice in "...et sä et..."? Do they mean the same thing?

No, they are completely different words! The first et is a shortened spoken version of the conjunction että (that). The second et is the standard negative verb for "you" (you do not). In written Finnish, this exact same phrase would be "...että sinä et...".

How do the verb forms oon and oo correspond to standard Finnish here?

oon is the spoken form of olen (I am). oo is the spoken form of ole, which is used here in the negative perfect tense et oo (standard: et ole, meaning "you haven't"). In colloquial speech, the verb olla often loses its -l- and the vowels stretch to fill the gap.

I learned that ylpeä (proud) requires the ending. Why isn't that used here?