Jup, that's a big problem for a small developer.
A possible (maybe temporary) solution would be Stable Diffusion. Just be clear about the use of it and negative feedback should be imperceptible.
If you don't know what to expect just check here: https://civitai.com
... and it can also create nsfw stuff ;)
tbh, given the profoundly negative response so much AI art gets, and the ethical issues with training data, and its inability to do things like "replicate an original character's physical features between separate prompts", it really doesn't seem worth it to try to generate AI-generated character sprites, much less attempt any kind of CG art.
Thank you! I was definitely not going to be interested in playing this game had it included ai images. If you can't afford it, there's no need to add it. Ai "art" is in no way a form of art. For, a robot cannot truly ever replicate human emotions and hardwork. However, there are quite a lot of people nowadays who draw great art with low expense commissions. So if you ever think you have the time or money for that, maybe you can contact an professional
