A little late to the party here, but the proof of concept repo is open source and available for perusing

https://github.com/akoutmos/sqlite_scale

@dimitarvp thanks again for the reference to dynamic repos. Using this info, I wrote an prototype library called DynDb to manage Dynamic Sqlite databases. Interested to get feedback re: API design and potential gotchas. Have a look!

#!/usr/bin/env elixir 

Mix.install([
  {:dyn_db, github: "andyl/dyn_db"}
])

# Write a Migration 
defmodule Migration0 do
  use Ecto.Migration

  def change do
    create table("chats") do
      add(:message, :string)
      timestamps(type: :utc_datetime_usec)
    end
  end
end

# Write a Schema 
defmodule Chat do
  use Ecto.Schema

  schema "chats" do
    field(:message, :string)
    timestamps(type: :utc_datetime_usec)
  end
end

# Interact with the DynDb
defmodule Main do 
  def main do 
    # The database file will be auto-created
    {:ok, db1} = DynDb.start_link(database: "./data1.db")

    # Migrate 
    DynDb.migrate(db1, Migration0) 

    # Query  
    DynDb.insert!(db1, %Chat{message: "HELLO at #{Time.utc_now()} UTC"})
    DynDb.all(db1, Chat) |> IO.inspect()
  end 
end 

Main.main()

Alex Koutmos played with something similar previously, maybe this is useful? Alex Koutmos on X: "Using Ecto dynamic repositories, a DynamicSupervisor, and a Registry, I was able to create a SQLite powered Phoenix app where every user has their own SQLite db and interacts with their own repo instance. I have now achieved the sharded webscale. AMA #MyElixirStatus https://t.co/3qJkQokooi" / X