Segregate frontend (ReactJs) and backend (Nodejs) of an ecommerce -- 2

I have an e-commerce webiste in MERN. Where frontend and backend code is not segregated and an older version of node js is used. I need to get both codes of frontend and backend in 2 different repositories and node version 17 should be supported instead of 14.

1. Segrigation of frontend and backend.
2. Upgrading node version from 14 to 17.
3. Fix compatibility issues. (Should run successfully)