Learn Portuguese (Portugal): O projeto depende de nós.

In Portuguese, the verb depender is always followed by the preposition de (meaning "of" or "from"). You cannot translate the English "on" literally here. Think of it as saying the project "depends of" us. Learning which preposition goes with which verb is a key step at this level!

I learned that nós means "we" as a subject. Why does it translate to "us" here?

After a preposition like de, you have to use a "stressed" pronoun. For "me" and "you", the words change completely (mim and ti). But for "us", Portuguese just reuses the subject word nós. So de nós means "on us".

If I wanted to say "depends on me", would it be depende de eu?

No, it would be depende de mim. While nós (us) and ele/ela (him/her) look exactly the same after a preposition as they do when they are the subject, the words for "I" and "you" change. You must use the special stressed pronouns mim (me) and ti (you) right after prepositions.

Why doesn't de combine with nós to make a single word, the way it does to make dele?