Have you looked at the Sidekick rules in TCoE? They offer a way to add NPCs to the adventuring party that are partly controlled by the players and partly controlled by DMs. Meant to make it easier to play with 1-2 players and to make it more manageable to hire specialists, etc Essentially Sidekicks have special character classes that make them far easier to manage than full PCs. (Animals can be sidekicks too!) See also the Essentials Kit.

— WinningerR (@WinningerR) January 1, 2022