Morgan Stanley's version is open-source at https://github.com/morganstanley/optimus-cirrus , although I don't know how practical it is to actually run yourself. (They don't go quite as far as having the code itself be bitemporal and kept in the datastore, but most of the stuff in the article exists there)
Well I doubt these solutions are very useful outside; from what I read what they have is a universal data store (that isn't hard to implement using current off-the-shelf OSS), something for financial instruments that has a compositional nature (you won't encounter much of that in the outside world), plus some other quirky features.
Of course, financial institutions have a lot of “secret sauce” - such as financial models - you’d never expect them to release.
But this kind of underlying infrastructure isn’t really “secret sauce”