Profile design makes something like that, look on their website under aerobar accessories

Couple options (I have the Profile one and the nice part is it is width-adjustable):

Vision Aerobar bridge:



3TTT Bridge


Profile UCM computer mount (can also work as a bridge)

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

Syntace Microlink (if you can still find one). It's narrower than most of the other options.

To be honest, I swear by using a bridge as it stiffens up the whole assembly massively and provides a little extra grip security. I use the syntace but scanned theirs in, 3d printed a narrower bridge and use their expander plugs.