Good question and apparently there is still a lot of confusion on this topic as it relates to K-1 visa holders already in the USA. Here's what ChatGPT had to say:
What the law and USCIS regulations still currently allow
K-1 holders who properly entered, married the petitioner within 90 days, and are otherwise admissible can still file adjustment of status inside the U.S.
For K-1 holders specifically, this matters because forcing consular processing abroad could create major problems:
separation from spouse,
uncertainty about reentry,
triggering unlawful-presence bars for some people,
inability to work in the U.S. while waiting,
and exposure to consular denials abroad.
That’s why immigration attorneys are reacting strongly to the memo. AOS for spouses of U.S. citizens has been a standard path for decades.
So at the moment, the “return to your country” issue is best understood as:
a serious proposed enforcement direction/policy interpretation,
not yet a blanket legally settled requirement for all K-1 green card applicants.