I wonder if the front-end for something like Steveslist really needs to be a single-page application. The problems with SPAs are numerous and well-known. IMO, the difficulty of developing a robust and efficient SPA is only justified if the application needs to run offline, which IIUC is not the case here. With traditional server-side rendering plus something like Phoenix LiveView or Blazor Server, I think most web applications can go very far without having to go the SPA route.
I thought this a well written and easy to read article. However, I couldn’t help thinking that they should start with a simple website using Rails, Django, Laravel etc. Respond to technical requirements and demand, rather than build a solution for some imagined technical scenario in 5 years. That there is more emphasis on “how” it will work, than on “what” it does for users, is of concern.