Antifungals promote bowel movements. Eating fiber such as rutabega or pumpkin can promote good digestion. Herbal teas such as chamomile are good for digestion and liver. Like Danny said, water is vitally important. If you are dehydrated, your insides will shrivel up making it harder for things to move (this is my opinion not scientific).
Digestive enzymes are an alternative to bitters.
There are lots of digestive aid supplements on the market such as l-glutamine, slippery elm, etc. Basically anything in the leaky gut supplement list (I can share link if needed its on sticky tab). There is a whole industry created for you to treat digestive problems with products from standard process, thorne, pure encapsulations, integrative thereauptics, etc. (just listing some top notch brands).
Also, reducing inflammation I have noticed improves digestion. There are lots of anti-inflammatory supplements out there such as cod liver oil, cinnamon, etc.
All trace mineral supplements improve digestion such as iodine, zinc, magnesium, selenium, etc. These are typically found in the clay products naturally.
One problem with the clay is its mostly only good for detoxing and not necessarily improving digestion, a lot of people have noticed constipation when taking it. When combined with psyllium which can have sharp edges, this isn’t a good situation for your gut in my opinion.
All prebiotics and probiotics improve digestion.
Also, how much do you chew your food? If you are not chewing your food 30+ times per bite then this could prevent your body from producing digestive enzymes. The food could have a hard time breaking down in your gut if you don’t chew your food as well.