If you want any of this, why don't you found a Verein and have open source activities as the purpose?
All in all I an very much against this. Mostly because I think Ehrenämter, as they exist now, are pretty stupid and pointless and because I strongly believe the state should not get involved with this at all.
In the USA, open source foundations can be non-profits, usually they are formed for scientific, and sometimes maybe educational purposes. (The allowed exempt purposes of a 501(c)(3), the most common type used for open source foundations, are "charitable, religious, educational, scientific, literary, testing for public safety, fostering national or international amateur sports competition, and preventing cruelty to children or animals".) There are other requirements that must be met for exemption as well.
I am curious how German and US laws differ in this regard, if you happen to know more about it. Thanks!
This is about recognition for individuals (which is much if what an Ehrenamt even is). Besides some very minor tax benefits, only applicable under certain circumstances, where you earn some money from your Ehrenamt activities, all this is, is an participation award for volunteer work.