Of late I’ve tried out the Translate You Android app. Not necessarily an endorsement of the app itself, but it offers a selection of 9 translator services, a few of which are libre.
Certainly LibreTranslate and Lingva are open source, probably a few more on their list. Give them a try and see which works best for you!
poVoq@slrpnk.net 2 weeks ago
LibreTranslate is a bit hit or miss depending on the language, but generally speaking it is quite good, but not Deepl level good.