The above study seems to imply that a gastro based infection of COVID is linked to mild symptoms though since cells in the digestive tract have far fewer ACE2 receptors compared to the respiratory system. So maybe it's the best way to catch the disease?
The digestive tract doesn't need to be infected to be effected. AFAIU, in some cases non-infectious viral particles (i.e. non-viable segments floating around in your body) have evolved to make you cough and sneeze through irritation, so it would be unsurprising if in some people they irritated other tissues or possibly even effected gut flora.
If this is in fact the case, then fecal material wouldn't necessarily be a transmission vector. Although it could be; it could be a vector even if the irritation was not by infection.
If we could somehow confirm that most (>95%) of gastro based infections result in mild symptoms, I wonder if that would be one way (although not a great way) to "immunize" the public vs a vaccine? Swallow the pill containing the virus and let it run its course to develop immunity?
This general strategy is called inoculation, or variolation.
It is, indeed, not a great way to immunize the public, as the patient becomes contagious, and can pass on full-blown infection to other people. It's also dangerous in its own right; 'mild' infections can progress to full-blown infections.
If the risk could be reduced 10-100X it may be worth consideration. I could imagine one of the crazier/more desperate countries trying this in order to get ahead long term (North Korea?).
The above study seems to imply that a gastro based infection of COVID is linked to mild symptoms though since cells in the digestive tract have far fewer ACE2 receptors compared to the respiratory system. So maybe it's the best way to catch the disease?