Hello Andreas,
you could have a look at MindSphere’s API “IoT Time Series (TS) Aggregates Service” (check it out here: https://developer.mindsphere.io/apis/iot-iottsaggregates/api-iottsaggregates-version-v4-whats-new.html)
With this API, you can make use of MindSphere’s aggregation functionality without having to import large datasets into your Mendix application. If you only require aggregated data in your app, I’d say this API is the best way to go for you.
BR
Philipp