The one I hear is good is NVDA by NVAccess, but it doesn't have AI.

Website: https://www.nvaccess.org/about-nvda/

Source code: https://github.com/nvaccess/nvda

I would be fairly surprised if you found an open source screen reader that had AI built-in.

It would likely have to run locally if it was open source.

Typically companies don't make their stuff open source, and non-profits are unlikely to host an AI for you because of the cost. It's unlikely to run locally as the cost for that model to run and download size may make it unusable or impractical for some hardware. Typically screen readers need to be accessible to everyone, and therefore need to run on very old and / or cheap hardware.