A note jumping through the legal/paperwork hurdles with large companies: be prepared for it to take a long time. A very long time in some cases.
It all depends on who you’re working with, how big the company is, and how much money the deal is worth.
IMO going through that successfully is also sending a signal that you have sufficient endurance - there's a large risk for a corporate to sign up for a long contract with a startup, they don't know how long you're going to be in business for. If the startup doesn't have the appetite to spend 2-3 years to get a contract over the line, then they aren't going to be a stable partner for the long term.
You need to also have sufficient numbers of small/medium scale deals so you're not 100% relying on elephant hunting.