Now that it’s firmly entrenched as Microsoft branding you may want to reconsider. Soon, people searching for “AI Copilot” aren’t going to be able to find you.
Microsoft is using the Copilot term everywhere - in GitHub, Visual Studio, all the Office apps etc. They have rebranded the Power Platform Virtual Agents builder as "Copilot Studio", and chatbots in your projects are known as copilots.
I would be very surprised if you didn't receive legal challenge to your use of the name, if you grow in popularity.