B2B store setup - Connect frontend(jsonc theme blocks) with node backend

Hi There,

I started off with installing b2b store theme using this as reference.

b2b store theme - git clone GitHub - vtex-apps/b2b-newstore-theme: VTEX Store Theme demonstrating some of VTEX's B2B capabilities in a practical and objective way
node js service - service-example.git

I am able to customize the theme blocks but I want to know how to connect the theme blocks with the node service. I tried VTEX link on both these projects but unable to figure out how can I make api calls from theme blocks other than changing props in theme block.
Is there a better boilerplate which details about theme blocks and node js service?