Hello @dems_i, we have a English to Ukrainian model, but it isn't released yet. It would be great if you could test it in Firefox Nightly and let us know if you are satisfied with it.
Anyway, we are going to try to improve it this year to be more confident that it is good enough.
I think the ability to translate a page from another language to Ukrainian would be a great feature for the 45 million native speakers of this language 🇺🇦. also not clear why there is an option to translate into Russian??
btw until such a feature appears, you will have to give preference to Google Chrome.