Can I buy treasuries on Fidelity?

Excuse me, I'm wondering if it's possible to purchase treasuries through Fidelity? I've been exploring different options for investing in government securities and Fidelity seems like a reputable platform. Could you please clarify if this service is available on their platform, and if so, what are the steps I need to take to initiate a purchase? Additionally, are there any specific requirements or limitations I should be aware of before making such an investment? Your guidance would be greatly appreciated.