In fact, the approach you used for actor (using GWT) is no less applicable to us (using pyjs or rapydscript - see https://medium.com/@ZeroDB_/zerodb-js-zerodb-in-the-browser-...)
Protocol and some clean reference implementation without dependencies will be neat.
Reference implementation without dependencies would be just a more cross-language rewrite of these dependencies though, so would take quite a while. Good news is that authors of ZODB which we use as a dependency are willing to do that (and already do that) in a more cross-language way.