> Does that mean signing up with you gives me an account with those banks, or do I still have to sign up with those banks independently in order to use your service?

Neither. The funds are held by those banks, but you won’t ever deal with them directly nor have any login to them

> Would I need to fly to the US to get this started, or would a zoom session plus all the relevant ID's be enough?

You just sign up online and provide documents. No zoom sessions.

If you have the relevant documents signing up should take ~15 minutes