Yes you can make dua in sujood in any language provided you don’t know Arabic.

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The sitting between the two sajdah is a pillar while the Duaa is obligatory.

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It is more rewarding for him to join the congregation in the masjid but if the masjid is far away or this is for Tahajjud, this is permissible. Kindly refer to the following link(s): https://islamqa.info/en/2034

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