If you want to search for suitable and already published data for your research project or are looking for a repository for your data, a search via the portal re3data.org, which lists a large number of repositories, is recommended. In addition to a keyword search, the repositories can also be filtered by subject.
With RIsources (RI = Research Infrastructure), the German Research Foundation (DFG) offers an information portal on scientific research infrastructures that provide researchers with resources and services for planning and implementing research projects.
The "Zenodo" repository is interdisciplinary. Here, too, you can store your data and assign a DOI.
DataCite e.V. is an international non-profit association that offers services and know-how around the referencing and findability of research data.