Keep in mind this is a voluntary position and adjust expectations accordingly.
> I've made some minor contribution to the l10n-germany  repository and
> would continue my work on migration and fixing existing modules.
> Unfortunately, the PRs are open for weeks and nothing happens.
weeks is not long for a low activity repo like this one.
> What can I do to get my (and other) open PRs reviewed and merged? Isn't
> there any maintainer of this repo? Did I miss something?
review/test other people's work, I don't see you doing any of this.
Maintainers also tend to appreciate picking up things like
if you want to get a standing there to join the group of maintainers
Your partner for the hard Odoo problems