Well, this sentence makes me feel less pleased with myself for learning Norwegian! Apparently, it's nothing special. Wahh!!
So forgive me if I'm just stupid, and I don't know if this is an accepted translation or not...
but I feel like it should be "Anyone can teach their self Norwegian?"
I don't' know
not their self, in this case it should be themselves (most likely)
or themself, him self or herself.
Anyone can teach himself .., anyone can teach herself... or anyone can teach themself. (neutral gender but a bit odd).. More common for neutral gender would be Anyone can teach themselves...
Would "Everyone [...]" make sense? I find it similar, but I think it is a little different.
I wrote "Anyone can learn Norwegian" and it's accepted.
My understanding is that "lære" means to teach (false friend! ;) ) while "lære seg" (lit. "teach oneself") means to learn.
In your sentence I think the problem is "whoever" as it has a different meaning than "anybody/anyone".
That doesn't work in English. It would mean "Any person who...". For example, "Whoever can learn Norwegian will have a better time in Norway."
The word does a better job of standing in for "anyone" as an object at the end of the sentence: "I can teach Norwegian to whomever/anyone".
I see that now, I'm surprised I didn't at first, being a native English speaker haha but thanks!
Informally, "whoever" can stand in as a simile for "anyone". It's a dodgy way of talking but I would wager quite a few people would understand the meaning, especially if you emphasize the "whoever". A bit like people understand when someone says "That ain't worth nuthin".