Somebody should add Finnish to the selection of languages available to English Speakers
I would love to see that too!
While you are waiting for a Finnish Duolingo course, check this user created course out: https://www.duolingo.com/comment/9877177
Check the language incubator regularly and if you know someone who can help create this course (They must be fluent in both the new language to learn and the language that it would be learned from.), please send them to apply to create it: https://incubator.duolingo.com/apply