I think for biomechanicals, you want nonorganic materials for any parts subject to high stress, unless you want to go really high tech and have an organism that incorporates large amounts of metals, ceramics, polymers, etc. directly into its framework. An organic brain is way faster for pattern recognition and language processing, could be paired with a regular computer for number crunching.
Perhaps an alien culture has contacted Earth, but hasn’t arrived yet. Maybe they are friendly and send information on new technologies, maybe they are coming to assimilate Earth into their empire, and Earth has to figure out something before the aliens arrive.