Ainu language option.
I think you have to ask yourself if that's worth it. There are roughly 25k (?) Ainu alive today. of which +/-300 still speak Ainu. Only a handful are native speakers.
You won't find any teachers on here or websites like Italki I fear.
Finding Japanese people who speak Ainu, I think you can forget about that as well. I've lived in Japan and have never met a Japanese person who can speak Ainu. I've never even met one who is interested in it. Native Ainu speakers are almost non existent.
With respect to using Lingq for Ainu, does Ainu even have any written work to read?
I think your best bet to get started is probably be to learn Japanese first and then to look either for people in Japan to teach - probably through university or affiliate programs - or to find basic Japanese textbooks. Or perhaps some material is available in russian as well...?
A more die-hard method would be to try to gain access to Ainu people in Japan through intermediaries and look if there's a way to join them and learn directly from them.
edit: see following on youtube for some spoken Ainu lessons and culture info, but it requires knowledge of Japanese: https://www.youtube.com/watch?v=X1l4duE9s14
I want to learn it to help preserve it. One of the reasons is that they are the closest to an Indigenous group Japan has. They have an interesting culture and the quilted coats they have are beautiful. Maybe I will have to contact the museum back in Hokkaidou. I thought a resurgence was happening again in learning the culture was spreading learning the language again.
I hope we see more Indigenous languages added on Lingq...from Quechua, Cloo, Dinae, Creed, Mayan and many others. It would be a shame to see so many lost, from cultural importance to important medical knowledge lost.