Until AI models on the device will become a standard I really doubt you’ll find a viable alternative, since then it will always be someone’s server you send your pictures to, it’s the matter of who you trust more, a well established corporation which will profit from your content or some shady company/startup that will do the same but in less controlled environment

I mean, yes, Youdao, but I am not sure how well a Chinese translation app would would for you.