Earlier quoted context omitted.
It seems to me there are three possible ways law on the internet can work, to include ill-defined hybrids between them. Please let me know if I've missed any: 1. The law where a service is hosted applies. Entities in other legal jurisdictions may not be allowed to do business with the service (e.g. run ads on it) if it doesn't follow the law where they're located. Cost: people may be able to access content that's ill…
If you do business in a country, laws of that country apply to you. Selling apps in that country would count I presume. Part of the threat from the german government was to have GPlay and Apple delete the app from german storefronts. I don't see how that is much of an issue.
I can get the Android version from Google's store, which is uncontroversially subject to German law because Google has physical offices and a financial presence in Germany. I can also download it from telegram.org, which to my knowledge does not have a physical or financial presence in Germany.
Germany probably has the legal authority to order Google to stop distributing the Telegram app and can use that authority to pressure Telegram. What remains unresolved is the degree to which Germany can act against Telegram directly.