Below is a recipe I've been using for a while now that I lifted from this old reddit thread. I've found it works great as an addition to most soups, sauces or gravies either alone or as a flavor booster (honestly, nutritional yeast by itself will do that to a large extent and is seriously underutilized).
Blend all ingredients to a powder. Dissolve 2 teaspoons per cup of boiling water, then adjust ingredients and ratios to taste. Poultry Seasoning can also be a good addition. Store in an airtight container.
*I'm not a fan of paprika, because it always seems to disappear when combined with other ingredients. Old Bay, on the other hand, complements whatever it's added to without overpowering.
This is undoubtedly better than what you will buy at the store but for those as lazy as me I've found that a large portion of chicken bullions are accidentally vegan.
Those little microbes pack a punch! Other yeast extract such as vegemite and promite, or fermented foods such as soy sauce and miso, will work similarity. When it comes down to it, we're just looking to add glutamates in one form or another.