Debating whether to forge Adamantine shield

Hey, first playthrough here, about to battle Grym. I'm not sure if I'll want the medium armor or the shield. I'll definitely get heavy armor for Lae'zel.

Looking at shield proficiency, I'm not sure I'll use it beyond Shadowheart. The classes/subclasses/builds I'm interested in wouldn't use shield:

• Barbarian, I thought they'd be two handed or dual wield
• Bard would Sword Bard Astarion, not Valour.
• Cleric, yes.
• Druid, won't play it.
• Fighter, Lae'zel is Great Weapon Master and will always be.
• Paladin, I'll probably try it with Lae'zel, Karlach or Shadowheart. Not sure if they always use a shield.
• Ranger currently is Gloomstalker/Thief Astarion with Titanstring bow and 19 STR offhand, so no shield.
• I don't usually run Gale because my Tav is a Sorcerer.

I thought Warlocks used rapier + shield but I guess I was wrong.

Am I missing some obvious good uses of shields? Otherwise I don't think I should take it just for Shadowheart and maybe a future Paladin which I'm not sure if they'd use a shield.

Of course I can always take it with the feat but I don't think I'd want to sacrifice a while feat just to equip an item.

Basically I'm asking more experienced players for help with how to play with shields.