So, in other words, you have intentionally tried to break your system and you succeeded. So, congratulations? pacman and apt have a different feature-set. Hand

So, in other words, you have intentionally tried to break your system and you succeeded. So, congratulations? pacman and apt have a different feature-set. Handling a neglected system and recovering from terminated upgrade are explicitly not what pacman does. If you expect such features from your system, why did you install Arch in the first place?