I’m a little busy right now, but as this is very exiting a few quick thoughts.
I’m thinking about the exact same thing some time now. Then I found Storex, see Storex - Frontend store with the state on the backend - #8 by Sebb and played a little with that. Do you know it?
I have some demo code where I rebuilt the solidjs-store example
in Elixir.
The only problem right now is, that the Storex store does not play nicely with solid’s reconcile and from - one has to clone all data coming in. But its good enough to see that this is a great approach.
Very much looking forward to what becomes of this, and eager to help, will look at your demo asap, ie next year 
