I don't see a way to add inclusive pronouns to German without inventing new words - which players could do of course.
But there are many accepted ways in German to combine male and female forms of nouns. The biggest gender challenge in our language is that there are obligatory male and female forms of all descriptions for human beings. While English speakers have an actor and an actress, we also have a teacher and a teacheress (Lehrer/Lehrerin) and so on.
The problem is that in everyday language the longer female form is often left out thus making non-male persons invisible. If you see a mixed group of teachers, you often simply say
die Lehrer (the male teachers)
instead of
die Lehrerinnen und Lehrer (the female and male teachers)
Luckily in written language there are multiple accepted combined forms that all people can identify with like
Lehrer*innen
LehrerInnen
Lehrer_innen
I'm pretty sure that this will be the German equivalent to the pronouns project.
