Wow, looks like there's a ton of choices here I haven't looked at. For iterate.world we use replicate but just added kandinsky from runpod. Thinking about switching everything to runpod because it's 5-10x cheaper and we only use models that they have anyway.

There's one I won't share that's is now defunct but you could use any diffuser's compatible project on Hugging Face, which was such a cool feature. I wish someone (cheap) would implement this!

edit: just looked at banana.dev in this thread, their templates look closest to the HuggingFace integration though I don't think they have webhooks.