Those openings lead to spaces that are not "inside" the body, though. For deuterostomes like humans, the digestive tract is still "outside" in a lot of important ways.

Well good golly miss molly, that's a word I had never heard of. Thanks!

For the lazy it basically means as embryos our anus forms before our mouths do. So we have to talk out our asses before we even leave the womb!

Not remotely the same thing.

Pesticides and micro plastics are equally foreign even if not absorbed/ingested in as one big unit. Besides, in modern medicine, implanting devices in organs (ex: pacemakers, valves, electrodes) isn't unheard of?

I think you narfed your own point by using objects getting into various pores and openings.

Pacemakers are somewhat similar devices that get implanted into bodies and still effectively are "foreign objects".