Here is a list of associate members, https://ec.europa.eu/info/funding-tenders/opportunities/docs/2021-2027/common/guidance/list-3rd-country-participation_horiz

Here is a list of associate members, https://ec.europa.eu/info/funding-tenders/opportunities/docs/2021-2027/common/guidance/list-3rd-country-participation_horizon-euratom_en.pdf https://ec.europa.eu/info/funding-tenders/opportunities/docs... which also lays out some of the terms. If you scroll down there's a list of countries which can participate and who are automatically eligible to apply for funding too. So the EU, at least bits of it, despite all the talk of gardens and jungles, is still a force for good in the world.