Have you tried Tachidesk-server? It’s a fork of the tachiyomi app but as a self hostable, you can try downloading your mangas from there

You can make your own infinity app using your reddit API, just follow this guide: https://www.reddit.com/r/Infinity_For_Reddit/comments/14c2v5x/build_your_own_apk_with_your_personal_api_key_in/