German domains are great if you are focusing to build up geotargetted german sites, specially if you see that most of the incoming links to those domains are also geotargetted
But take one thing into account that could mistakenly be taken wrong. Sometimes you could build a lot of reputation, just through citations, that generally are relatively easy to obtain.
So if you find the typical local commerce site with a good reputation and a ton of links, but mostly coming through citations (maybe this business bought a package from a citation builder) then avoid id.
But if you find a site, with several references from specifical german news sites or relevant german blogs, then it would be much better, than just a random global page with links from all around.
But this only applies if you are willing to geolocate your reputation. If you are going to build a site talking about software, you can buy domains from just anywhere in the world specially if those domains where also relating to software.
In this sense, think of PBN domains as guest posts sites. Guest posts sites that are completely managed by yourself.