npm install nextjs-progressbar
または
yarn add nextjs-progressbar
/pages/_app.js
import NextNprogress from 'nextjs-progressbar'
<Component {...pageProps} />
↓ NextNprogress を追加
<NextNprogress
color="#3b7d6b"
startPosition={0.3}
stopDelayMs={200}
height={1}
showOnShallow={true}
/>
<Component {...pageProps} />