It’s not too inherently unbalanced either. I know I’m late to the party here, but in the module Wild Beyond the Witchlight, there is a random encounter which grants a choice of skill proficiencies to added to a character’s skill list, called the Astronomer’s Throne.

It’s not inherently unbalanced either.

In the module Wild Beyond the Witchlight, there is a random encounter - called the Astronomer’s Throne - which can grant a choice of a skill proficiency to be added to a character’s skill proficiency list.