Does the Theravada canon have such ideas anywhere at all?
This is a far-fetched example which barely answer your question but IMO the Buddha himself kind of returned to the market-place: not as a tradesman nor even a customer, but he did leave his solitude.
The description could almost fit him:
- In the World
Barefooted and naked of breast, I mingle with the people of the world.
My clothes are ragged and dust-laden, and I am ever blissful.
I use no magic to extend my life;
Now, before me, the dead trees become alive.
Comment: Inside my gate, a thousand sages do not know me. The beauty of my garden is invisible. Why should one search for the footprints of the patriarchs? I go to the market place with my wine bottle and return home with my staff. I visit the wineshop and the market, and everyone I look upon becomes enlightened.
Any resemblance can't be entirely accident, presumably, to the extent that he was ever a role model for Buddhist enlightenment.
A few things seem to me anachronistic.
"I use no magic to extend my life" -- is that a reference to (rejection of) some Taoist-immortality-magic or -obsession: which, I'm not acquainted with, but might have been important when it was written?
Wine is forbidden in Islam too, but apparently some Sufis use "wine" as a metaphor for a divine love and loss of ego. That's esoteric (and orthodoxly a heresy) in Islam (it also reminds me of a family story: that when my grandfather bought a house in Morocco he met a "hereditary saint" there who was allowed to drink wine because the wine would turn to water in his mouth), but really I don't know anything esoteric especially about Buddhism. Apparently there was a Sufi doctrine which said that, "Drinking 'wine' depends: on how much, and who with", but beware I think that advice is Delphic.
Another idea is that some of the versions of the ten bulls talk of carrying a "gourd", depicted as (or, who knows, perhaps mistaken for) a wine gourd: but which (a gourd), someone else wrote, is a metaphor for emptiness.
Sunyata might be a bit anachronistic too, i.e. a tenet developed in slightly later schools.
It's a bit difficult to imagine the Buddha pulling a pint in the pub with his friends. If I see someone doing that though, then as long as they're not doing harm I'm conditioned not to say something like, "You're a bad man: you shouldn't be drinking."
Is that what "everyone I look upon becomes enlightened" means, i.e. non-duality, and to whatever extent I hope to become enlightened, other people become so too? I mean there are two ways to see that: being "looked upon" (or talked with) helps to lead the seen person to enlightenment; doing the looking helps the seeing person see there is enlightenment (perhaps some "Buddha nature") already.
On the other hand maybe drinking is harmful, and if I were wise and kind and selfless then I would mingle with them there?
Anyway that leads to this other answer about non-duality which I think you already know, which says there are real differences between Theravada and Mahayana practice. And so I present that answer as saying, "No, I don't think you'll find exactly the same 'returning to the marketplace' within the Theravada Sangha."
It is reinforced by the belief that one who has such attainment will leave the family
One of the Zen stories I admire is Nothing Exists. I like it because it reminds me that it's not to do with theorizing about the nature of external phenomena, but it's more about being prepared to behave myself.
There's a quote I read once, I haven't found it again since, someone was asked "Why won't you become a Christian?" and replied, "If you mean 'Christian' like your Christ, it's because I don't have the courage. If you mean 'Christian' like you, it's because I wouldn't want to be."
Does that make sense, assuming you know the Christian metaphor for marriage? I don't know whether you are or have ever been married, but how could you expect to control two people if you don't even control one?
Actually I have the belief that Siddhartha left his family, not because he had such attainment but because he desired that attainment.
Conversely, Is That So? might be a story of someone who already has some attainment and subsequently acquires a family.