wondering do you have any idea to modernise Spree/or Solidus’s erb based frontend, possible to add Tailwind or Vuejs to the Spree/Solidus project?

Not really familiar with Tailwind, I tried their Vuejs frontend and it's very far from finished, I would strongly advise against using it at this point, unless you want to spend a lot on development yourself. I think the Spree frontend is not too bad with Turbolinks enabled and I see no reason to go for something like Vuejs.