We watched both of these shows recently as well. I enjoyed them both, but they both did very poorly in South Korea. The King: Eternal Monarch was visually well done and I like time travel and sci-fi concepts but the ending was a typically rushed like most kdramas.
Vagabond had issues getting to TV and it was extremely expensive to make. Since it received low ratings and mixed critical response, it's unlikely it will ever get a second season.
Currently, making our way through Crash Landing On You which is also on Netflix but unlike the other two, was extremely popular in South Korea when it aired.