How to add a salty/bacon flavor and texture to vegan collard greens?
As a vegetarian, I regularly try to compensate for the lack of meat in a normally meat-containing dish using a number of methods, though I feel none can truly replace the addition of meat perfectly. In my experience, duplicating the effects of the addition of meat to a dish requires considering individually the effects the addition would have. 

First I'll address the fat added. Since the lard present in bacon is high in saturated fats, you can attempt to duplicate that using vegetable oils that are high in saturated fats, like hard margarine or palm oil. While I wouldn't normally advocate with using an oil specifically because it has higher saturated fat content (for health reasons), in this case it will likely help the quality of the finished greens. Consider using a smaller proportion of the more saturated fats by adding in a lighter/healthier oil, like canola or grapeseed, as a portion of the added fat. There is no single rule for getting the fat content of a dish like this right, and it's often a matter of taste.

The smokiness added by the bacon is also a consideration. While liquid smoke could work, the volatility of the product can contribute to the flavor getting poorly concentrated in the food. I have had good results with both smoked salt and smoked black pepper in concentrating smokiness in a dish, and I have found that adding either more near the end of cooking encourages the flavor to be retained more prominently.

For the savoriness added by the aminos in the pork, there is a wide variety of vegan options for its substitution. A good place to start, in my opinion, is to use a vegan not-meat bouillon (e.g. from Edward &amp; Sons) as the base of the broth. The addition of nutritive yeast (and to a lesser extent mushrooms) can also help infuse the broth with umami, and is a common ingredient in vegan broth preparations. If desired, the addition of liquid aminos (e.g. Bragg's Liquid Aminos), and/or MSG can help further improve the savoriness of the greens.

For the texture added by the bacon itself your intuition of using TVP or vegan bacon is likely the way to go. While neither adds much flavor itself (vegan bacon being far more mellow in its baconiness), they are probably your best bet for duplicating a meaty texture.