I use newsboat (console based reader) and sync it’s config and database with syncthing. I don’t do this on my phone, though I’ve considered setting it up. It is available in termux. I don’t think it’ll make for a very pleasant mobile experience though. But, it’s a solution that meets your criteria.
The nuances of this are beyond me, but I feel like it’s likely this would eventually be overcome.
Your best protection from having your images manipulated is to keep them off the internet if at all possible (we can only control what we post).
Basically I’m saying to treat the internet as hostile. Which is unfortunate, but accurate.