If I had to go with a custom design, I'd use HighCharts (free for non-commercial use) or ChartsJS (free), which already have these basic functions (interactive hover tooltips with supplementary data) built in. Just declare your data variable and specify your chart type, and that's it. You can also modify the CSS to change the look and feel. Non-coders could build a dash in Google Data Studio, PowerBI or Tableau and export it for embedding on the web.
Don't get me wrong, I've seen Mike Bostock's D3 gallery and yes, it's ideal for making incredibly elaborate, artistic data visualizations. But a line chart should be simple.