As you have asked this question, I assume that you already have an idea about bilateral agencies. If not then, here it is the term bilateral means “two-sided” and refers to organizations that operate directly between two well-defined parties, typically, two countries.
A bilateral agency may restrict its interactions to only two countries. However, a bilateral agency can also be a vehicle through which one country interacts with numerous other countries on a one-to-one basis. The bilateral agency receives funding from its home country’s government to then be used toward a developing country.
Returning to your question: Yes, smaller NGOs are eligible to tap funding from large bilateral agencies.
Most bilateral donor agencies have funding schemes targeting NGOs and civil society organizations. The United States Agency for International Development (USAID) frequently announces Request for Proposals (RFPs) where local, international and national NGOs can actively participate and receive funding for a wide range of developmental activities. The Global Development Alliance is one such program that believes in establishing public-private partnerships for sustainable development, and NGOs are essential stakeholders in it.
To start mobilizing funds from bilateral donors, NGOs first need to have a list of these agencies. As all types of bilateral agencies will not fund projects in your country or for your specific area of interest, you need to do some research.
To get an idea of how to research bilateral donor funding, please visit https://www2.fundsforngos.org/featured/can-ngos-apply-get-grants-bilateral-donor-agencies/