OK, so the armorer artificer (UA) specialization states:
Lightning Launcher. A gemlike node appears on one of your armored fists or on the chest (your choice). It counts as a simple ranged weapon, with a normal range of 90 feet and a long range of 300 feet, and it deals 1d6 lightning damage on a hit. Once on each of your turns when you hit a creature with it, you can deal an extra 1d6 lightning damage to that target.
Page 195 of the PHB states:
When you take the Attack action and attack with a light melee weapon that you're holding in one hand, you can use a bonus action to attack with a different light melee weapon that you're holding in the other hand. You don't add your ability modifier to the damage of the bonus attack, unless that modifier is negative. If either weapon has the thrown property, you can throw the weapon, instead of making a melee attack with it.
This, to me, implies that the artificer can use a shield, have his gem-node on his chest attack, and still has a hand free for an off-hand thrown weapon attack (as long as it's a simple weapon). The fact that one of his infusions can allow boomeranging thrown weapons make this viable if, you know, it's viable.
Anyone have any insight?