Is it possible to transfer the PKC licence of to the new device and reinstall the SW on it in case of a later PC change/replacement?

Yes, you can. Here is a link with the procedure: https://answers.microsoft.com/de-de/msoffice/forum/all/office-home-and-student-2019-auf-neuem-pc/93276b37-aac5-4e12-b90b-a233d606b826