Hi Gert,
Greetings from Syncfusion.
No. We don’t have support for templates in our Blazor components currently. We are already working on this feature and it will be available in our June 10, 2019 patch release. Until then we appreciate your patience.
We will get back to you once it is implemented and rolled out. Also, you can track the status of the feature in the below feedback link
Regards,
Pavithra S.