Spanner Omni, a downloadable version of Google Spanner

I thought this existed already, but I was thinking of AlloyDB Omni (https://cloud.google.com/alloydb/omni)

I have not seen anything about pricing (when running on your hardware). Anyone else found anything?

It is preview version at the moment - my take is the pricing will come later close to GA

Is it closed source?

Yes, it is closed source.