Dev, this is the best solitaire implementation I've seen since Windows 95. BUT
You fucked up Klondike, the basic solitaire game. Like, game-breaking fucked up.
You're not supposed to be able to play any card but King into a blank space.This is the only reason that it matters that the cards are piled in the 1-2-3-4-5-6-7 pattern. If you take from a lower pile, you make space for a king, but potentially end up with a dead, empty row if you don't need a king. If you take from a higher pile, you keep revealing cards, but you might not have the space you need for a king.
Without this rule, every pile is functionally equivalent to every other pile, and you just start revealing cards from the left every time (because if you empty a row you can always just pull the top card from another row into that empty spot).
The result is that the game is way easier than it should be, and (if the player thinks it through) loses some of the bare-minimum strategy that's part of solitaire. I would humbly request you consider changing this small deviation from standard play, especially since it is in the mode most players prefer.
With that fix, I think you could call this the perfect playdate game, one which should belong on every device.