1 million points

[nordlicht]

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https://data.opendataportal.at/dataset/dtm-germany ,
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Sonny's data sets are scaled to SRTM1 resolution which is still the commonly available resolution for large areas, despite higher resolution data available locally.

So far the OP has not indicated which area he is looking at, so no chance to point him to higher resolution data.

My choice of tool would be Global Mapper as it has powerful and comfortable elevation data handling capabilities.