A few alternatives to Duolingo (which hasn't been that good for a while now)
So here are some tips
Drops app - Originally from Estonia, now a Kahoot! company which is from Norway.
In few minutes a day for unpaid version it builds your vocabulary and you can also search by the topic. They offer wide range of languages.
They also support Ukraine.
Preply - Tutoring platform focused on languages originating in Ukraine. It is like a marketplace where tutors offer their language services and you can book tutor for language you want to learn.
Any VHS in Germany. They do online courses that include an app that you can keep using after the course has finished. The VHS in Neukölln is particularly good.