Where is this Nominex exchange located exactly? I mean in what country?
Is there any people that can't register or have restrictions, like US or others?
Based on CMC:
Launched on 28.08.2019, Nominex is a centralized exchange based in Seychelles (Suite 1, Second Floor, Sound & Vision House, Francis Rachel Str., Victoria, Mahe, Seychelles.). It claims to be licensed by the Estonian Financial Intelligence Unit (FIU).
And, base on their "terms of use" page 4 US is one of the restricted countries:
https://nominex.io/docs/nominex-terms.pdf