Has it been? I just got the email from Steam a few hours ago that it’s Live now. They must be really late to notify everyone in that case.
Looking through the community it looks like they had originally planned to release the demo today, but ended up releasing it early on June 5th, and the game will only be available to play until the 16th.
Edit: typo
Out of the 133 countries where Helldivers 2 was previously locked out of, now there are only 7:
1. Belarus
2. Cuba
3. Iran
4. North Korea
5. Russian Federation
6. Syria
7. Viet Nam
https://steamdb.info/sub/906471/
Update: now there are 8… Japan was added to the list: https://steamdb.info/sub/137730/info/
However it looks like Japan has its own individual game package so players aren’t actually locked out over there.
Edit: formatting