Ukrainian is a tough language, not least because of the past two centuries of the land's history, torn between Austro-Hungarians and Poles and Russians and Soviets, mean that its current form (and how best to teach it!) is still a matter of some debate. Taras Shevchenko (1814-1861), whose literary heritage is regarded as the foundation of Ukrainian literature--and, to a large extent, the legitimization of Ukrainian as an independent language--was jailed and exiled as a revolutionary for daring to honor his own language as a worthy medium of expression. Most late-life learners of Ukrainian quickly become aware of this political resonance in their learning choice.
All that said, it's a beautiful language, Slavic but sometimes described as "the sixth Romance language," with beautiful rolled Rs and many, many vowel sounds. The nightingale is a prized national symbol. What kind of a lunatic nation takes a tiny brown-feathered songbird as their national emblem?
--Duolingo has a short learning tree (which includes ~⅓ the number of lessons as its French or Spanish counterpart). A fine place to get started.
--Glossika has a full 5,000 spoken Ukrainian sentences--voiced by one of the harshest speakers of Ukrainian I have ever heard. It's only free for 7 days, but is a great resource for improving one's ear. Caveat: it does not exactly further one's sense of the famously poetic character of the language.
--The UK Ukrainian Language organization is an excellent source for beginning pronunciation and for reading. The first three lessons are particularly helpful--before it launches into daunting immersive mode!
--Anna Ohoiko has a beautifully put together collection of language lessons and podcasts at Ukrainian Lessons. This is a free resource, with extras that can be added for a charge. This site has been active for a few years now, so there it a lot of content.
--for flashcards, Anki has some useful language decks (though Ukrainian does not rate as one of their top languages). Access to content requires a log-in. I find the ☀️Ukrainian Language Vocabulary: Illustrated deck particularly good--because it is my own creation and reflects my personal idiosyncrasies.
These sources—they subtly contradict each other, and it is, I find, that peculiar disorderly subtlety that offers my biggest challenge to learning Ukrainian. What is this language I am learning? A Russian influenced variant? A modern artificially nationalist one? Certainly it's not the "pure" ancient tongue of my forebears.
And yet, I find myself enraptured. Between the 20th century diaspora and the last 30 years of Ukrainian independence--the culture and language are unsettled and in transition. It is a fascinating moment to participate in Ukrainian study.
Twin Cities Ukrainian Heritage Festival, "Ukrainian Fashion," September 19, 2021