Voting is certainly an interesting one, but we'll need a way to guarantee that the person who is voting is a citizen of the country, as well, as to prove that he is actually the one voting. For that we'll need some advances in authentication technology, too, perhaps tied to biometrics in some ways.

We can't just authenticate with an SMS code, or something "easy" like that, because SMS codes can be easily intercepted, which is why SMS-based 2FA is also not a good idea.

The best way I can think of right now is the government providing everyone a card with a Secure Element in it and usage of the card also requires a PIN. Rate limiters will also need to be added, so that if someone steals a card, they can't bruteforce the PIN. Basically, kind of like a credit card that only works when introduced in a machine and the PIN is given. So it wouldn't work like a credit card in the sense that you could also use it online. That would defeat much of its security.