In addition to @Greg_Deckler's suggestion, you can also import data from postgres database to data model, then import your file into Power BI where a dataset is created. So postgres data is also available in Power BI Service. You can take a look at supported data source in Power BI desktop or service:
@v-qiuyu-msft - Thanks for clarifying, that was poor language on my part that postgres is not available in the Service. The proper language is that you cannot create a postgres connection in the Service, but it is supported for refresh when creating a dataset from a Desktop file. That's what I meant by my statement, but it was worded poorly!
Correct, the Service has a subset of data source capabilities rather than the Desktop. The Desktop has many more data source connectors that are not available in the Service. In contrast, the Service is the only option you have for utilizing content packs.