Shouldn’t this title be - build a webapp using ChatGPT API?
ChatGPT runs on a heavily modified version of GPT3 nicknamed “GPT3.5” that is also not available via API.
I wonder if one of the open models would work the same
While Stable Diffusion is pretty comparable to DALL-E 2 even on small hardware (such as M1 MacBook Air), this doesn't hold true for large language models. These need much, much more VRAM.