From the little I know about Tom Bombadil Tolkien kind of just created him but didn't make it super clear what exactly his purpose was. It seems to me that Brandon Sanderson took the concept that is Bombadil and changed it some and instead of having this character that's super powerful just sit in the woods he has him showing up all over the place in his universe.

Hoid in some ways feels a lot like Bombadil except maybe not as powerful? It isn't super clear how powerful Hoid is.

Both Hoid and Bombadil are very old. Both seem very wise. Both seem to be content in not causing huge waves to change the world even though they both seem to be able to do so if they want to.