a question - I have created a custom component using nextjs components. I tested that by pointing my project in plasmic studio to localhost:3000/plasmic-host. Now if I push my local changes to github, will plasmic studio pick up those changes even if plasmic studio no longer points to localhost?
No you need to host your next.js somewhere public so that Plasmic can connect to them. See https://docs.plasmic.app/learn/app-hosting/#app-host-in-production