It's possible to integrate the Highcharts with Next.js through react wrapper. You can read more about it here: https://www.npmjs.com/package/highcharts-react-official#highcharts-with-nextjs

In terms of creating a custom indicator there are some docs and tutorials here:

• https://www.highcharts.com/docs/stock/custom-technical-indicators
• https://www.highcharts.com/blog/tutorials/creating-custom-technical-indicators-financial-charts/