USAID and many other large donor agencies prefer to work with registered and established NGOs. So if your NGO is not yet registered, it means it does not have a legal identity to receive or manage grants.
Besides, the lack of experience of the organization will also make it ineligible to apply for the grant as most USAID-funded projects are technically advanced and require tremendous experience of past project successes. USAID projects are also highly competitive and your new organization may not be able to demonstrate uniqueness to win the grant.
So, it may not be a good idea to submit a proposal to USAID while you are still working on registering your NGO. It is better to wait for a while and instead focus on approaching small donors for small types of grants. You can refer to this guide to know more about approaching small donors: https://www.fundsforngos.org/guides/small-grants-ngos/
