Hey - I'm the finance lead at CEA, of which EA funds is one part. Anyone can donate to EA Funds, and you should be able to do this from Germany. Are you concerned that doing so means you're not donating tax-efficiently since the funds aren't registered charities in Germany?
If so, my colleague Sam wrote this post arguing that donating effectively might mean ignoring tax efficiency, and I agree, depending on your alternative.
For example, if you were planning to donate only to AMF, and if there was a German AMF you were planning to donate to (I don't know if there is) which would you give tax deductibility, then I think it's better to donate to the German AMF and get the tax deductibility.
But if you were comparing a general charity that would give you tax deductibility in Germany, and if you thought the EA Funds option (e.g. the Founders Pledge climate fund, the Long-Term Future Fund) was >50% better value for money than your alternative in Germany, then my view is that it'd be better to just lose the tax efficiency and donate directly.