Norsemen is like if Monty Python did a viking sitcom. There's three seasons. Strangely 3 is a prequel to 1 and 2. So if you were to watch chronologically you'd begin with season 3.
Lovecraft Country is pretty entertaining. The main characters are black people living around 1950, so racism is a prominent theme. I wouldn't call it preachy or anything. If you like a little horror tinged with sci-fi then check it out. I'm a fan of Lovecraft's writings so maybe I'm bias. But this isn't really following his stories so much as it's just loosely inspired.
Never heard of letterkenny.