The problem to use it in France is that there is regulatory barriers preventing to use it officially. In theory accounting solutions have to comply with rules that are complicated to follow with your own opensource solution!
[https://en.wikipedia.org/wiki/PEPPOL Peppol]
Is anyone working on something like that?
But there is also a requirement for certifying that the data of the software can't be altered, and you are not allowed to certify yourself. This is the bad catch 21 situation. Even if it was possible to ensure that data can't be modified on your computer, something like android protected storage, I guess most people would not like that because if you use open source it is to have control over your machine.
So the only solution is the "cloud"/hosted solution by a provider, but again, if you use open source in the first place, probably it is because you don't want some external people to have control over your data.
In theory, a pretty simple scheme of publicly posted cryptographic hashes would prove to anyone you send the data to (presumably tax authorities? Auditors?) that you haven't altered data. Maybe periodically post a running hash of the list of transactions. Even if that works in theory, I'm guessing it's hell to get it actually certified.