Yes.

Yes. I do speedrunning mostly just for fun, and I do most of my Duolingo lessons normally.

Yes, I sometimes use (virtual) flash cards to help me remember the words in the languages I do. I do a few flash cards, and add a few words to the deck after I do a lesson.

I don’t really get the question, do you mean like how do I memorize the words in a Duolingo lesson?

I have, once, but my channel isn’t as popular that I would be able to start a community of speedrunners just from my videos

Thanks, I think that it’s because probably some people speedrun Duolingo, but it’s just not popularized