If you're still looking for a developer for this milestone, I'm interested. My released Godot project is Desktop Reptiles:
https://store.steampowered.com/app/4699700/Desktop_Reptiles/
For a small first stage, I'd suggest first-person movement, mouse look, and sprint/stamina in one existing scene. My indicative rate is US$20/hour; I'd confirm a fixed price and delivery date after reviewing your project, Godot version, and expected behavior. Which gameplay system would you like to start with? PayPal works for payment.