Ask HN: What API should I build a realtime data viz on top of this week?

I’m about to have a rare childless week of vacation in a boring town with decent internet access, and I’d like your advice for what to work on!

I’m a senior-ish full stack dev (Python + React) and I’m interested in getting some experience with real-time data viz using Highcharts or AG Charts.

I don’t want to get bogged down in scraping but other than that I’m open to any suggestions for the project as far as:

    - data source
    - what protocol to use
    - whether to do JAM or SSR 
    - aesthetics/styling

Please don’t tell me to “take it easy”, I already knocked that out in the first part of vacay. :-)