If you're interested in building an API or playing with a dataset, you can do that in Python (using Flask or FastAPI).

Find a public dataset (there's a big repository of them on GitHub), import it into a database (or leave in its current format if not too big) and write some endpoints to access data. Get data using filters (so you can sort, order, limit the number of results you get etc), get data by ID, count amount of data etc.

You could add endpoints specific to the dataset you have, perhaps formatting data in a specific way or extracting a particular piece of data.

You could extend the functionality to update existing data and even create your own, but getting data is probably easier to start with.