Quote Originally Posted by JLandan View Post
A shield could be used as an improvised weapon (1d4) with no properties. The Scofflaw subclass of Fighter from the Humblewood setting grants proficiency with improvised weapons and gives them the finesse property. So, the shield could be used with Dexterity and is subject to Sneak Attack, but still not two-weapon usable.

With the Shield Master feat, you get a bonus action shove attack with the shield. So, with that subclass and feat, you could make an attack with the shield as an improvised weapon and then make a shove attack with the same, or another, shield as a bonus action. I would think still only +2 to AC though.

As close as I can figure to two-weapon shield fighting.
Or, without homebrew(but still assuming the DM lets you use your shields as improvised weapons): The feats Tavern Brawler and Dual Wielder (both PHB). Tavern Brawler grants (among other things) proficiency with improvised weapons, and Dual Wielder allows two-weapon fighting with non-light one-handed weapons. (technically Tavern Brawler is superfluous, as proficiency is not required even for two-weapon fighting, but non-proficient attacks are highly inaccurate).