Puzzle Quest 2 had a lot of different challenges for unlocking doors, picklocking doors or magically breaking barriers (match x amount of different colors to win, match 3 gems at the bottom of the board that you can’t move, or match gems on 80% of the board positions).
Same for putting out a fire in a house, certain bosses healing or taking damage from certain gems and status effects, certain parts of the board being locked or filled with skulls, etc.
Same for the treasure maps from GoW as a different mechanic - as long as the rewards are much better, maybe lock it to a few runs per day as well to make it not stale.
There’s plenty of inspiration that can be drawn from there 
That type of challenges would be a very welcome addition, and make the playing a lot less stale.
And I definitely agree that swapping out these daily gauntlets for something else would be a welcome addition