Czech is on mobile!
Thank you guys so much.
It rolls out gradually over time so it might not hit all your devices at the same time.
For example, we have two identical phones here, both of them online and up to date. One has Duolingo 3.82.1 with Czech, Klingon and High Valyrian and the other one has Duolingo 3.81.4 without them.
This is exciting! However as I am a PLUS member I am waiting for my monthly re-subscribe, in a couple weeks, then hopefully my 4 year old cellphone will let me update it and I can join a Czech club :)