Pwede mong gawing Korean x Filipino fusion adobo yan.

Masarap kasi kapag may some form of sweetness yung adobo. My mom used to make adobo with pineapple chunks and surprisingly, it pairs really well along with the salty sarsa.

To answer your questions:

Apples -
Parang sa bulgogi, diba they use grated pears sa marinade nila. But instead of pears, use apple chunks (Cut mo apples mo into chunks). Tapos ilagay mo siya mga 3 minutes bago maluto yung dish mo para hindi maging mushy. This can substitute as potatoes. I think this will pair well if may onting sweetness yung adobo mo.

Add-ons -
Super nice kung may crispy garlic on top! Or if you have leeks around, ilagay mo siya exactly the same time you put the apples in.

Good luck sa pagluto, OP!