What I am trying to say here is everything you heard or lived is 100 percent true but reality differs sometimes.
Of course! When I recently gave away guest passes for games, it was clearly and unambiguously stated in the description that they were only for RU+СIS, although they could eventually be activated by anyone. Like the keys themselves, they were not initially regionally restricted.
I just wanted to say two things: gifts from region to region work, you just need to keep that 10% in mind. Moreover, this rule applies even in different countries within the same region, I have come across this. You may not notice this at first, for example, for the first time it happened that the price was the same, and you gave something to someone, and then, (a conditional example), you made a giveaway on steamgifts, and you decided to give the game away as a gift, not a key, and boom - Steam says that it is not possible.
Second: you can change regions. But it is better to think several times first whether it is worth it or not
