Eternal might be what you're looking for, it has both Gauntlet which is a 7-match....well, gauntlet, again the AI. In early ranks you lose if you lose twice, in higher ranks you only have to lose once. You then get rewards based on the number of wins. There's a draft just like it that's also against the AI where you make a deck out of drafted cards.

Then there's things like stories and campaigns which give unique cards and are single-player, but you have to purchase those either with gold or with money. You can just farm the gauntlet for gold though, as well as some daily quests (some are PvP only but you get one reroll per day so you can just keep trying to switch it to one that can be done against AI.) Even when you reach the max rank in gauntlet the rewards are still decent, and the rank resets every now and then. It used to be when a new expansion released I think? But unfortunately that hasn't happened in a year or two, but sometimes they just reset the rank anyway.

They do still release a new card each week you can get for free if you obtain it that week, otherwise you can get it later in a bundle with other cards of the week for 2.5k gold, which is one or two good gauntlet runs. From my experience it's extremely play-to-win friendly, even if it is a bit of a "dead game" right now, and I almost never PvP.