Learn French: Accablé, c'est le nomade qui a trouvé l'oasis. - Overwhelmed, it is the nomad who found the oasis.

It agrees with le nomade (masculine singular). Even though the sentence uses the emphatic structure c'est ... qui, the detached participle at the beginning logically connects to the prominent noun it describes. In French, this doesn't feel like a dangling modifier the way it might in English.

What kind of implied meaning does the detached participle Accablé add to the sentence?

Placing a past participle at the beginning of a sentence often implies a cause or a concession. Here, it likely acts as a concession: despite being completely exhausted and weighed down, he was the one who managed to find the oasis.

Why does the sentence use c'est le nomade qui instead of simply saying le nomade a trouvé?

This is a structure called la mise en relief (highlighting). By framing it as it is the nomad who, the sentence strongly emphasizes the nomad as the specific hero of the moment, pairing dramatically with his exhausted state.

Is oasis masculine or feminine, and how can we tell?

Oasis is a feminine noun (une oasis), though its gender is hidden here by the elision in l'oasis. If we needed to add an adjective to describe the oasis, it would take the feminine form, such as l'oasis cachée (the hidden oasis).