That being said there is a joint declaration between the RC, EO, and OO churches that if one is travelling in an area where there is no church of which they belong, the person may receive communion in the other churches.
My EO friends tell me that their priests are not allowed to give communion to anyone who is not a member of their church, and if an EO person has communion in any other church, this is a very serious matter.
What country is this? I have found that the rules are not all the same, or at least enforced in the same way, across different countries.
The Orthodox people I know come from several countries and church groups (I think they're called "jurisdictions"?), and all said the same thing: No communion to anyone who is not EO, and no communion is allowed for an EO from a church which is not EO.
Things in the real world are not so black and white.
For example, in the Middle East, there are some parishes in Muslim areas where the faithful can only have one Christian Church and one service, so Melkite Catholics and Antiochians have a shared Divine Liturgy.
In the continental USA, you might not find intercommunion, but in Alaska, if a person is dying, the OCA will give the last sacraments to Catholics. However, dying Catholics would be expected to make a confession beforehand. This information was shared with me by an Orthodox Priest who used to serve in Alaska.