Hi Lang,
You said, “I can see that it’s possible to practice “swallowing one morsel of food” while eating, especially if I’m eating by myself..”
You should seriously think about how that is going to remove defilements from one’s mid.
I have written many posts discussing why concentrating on breathing in and out cannot remove defilements. Is this any different from that?
The first thing to do is to find the Tipitaka reference and see what it says. It is very dangerous to just follow someone’s instructions on how to meditate.
I think the true idea is to contemplate on the fact that death can come anytime, even while eating. So, one should really strive to do real vipassana (contemplate on Tilakkhana) at every possible moment.