Best language apps for learning Ukrainian?

Just want to give a shout-out to the customer service team at Polrail. I fucked up in ordering the train tickets, emailed them right after, and they fixed the issue in less than 10 hours (it was 2am their time when I emailed them).

I didn’t have to go all U-Haul on them, I was polite, deferential, and made a clear request. Problem. Solved.