Part of the realignment of US 166/400 east of Baxter Springs should now be open:

https://www.ksdot.gov/Assets/wwwksdotorg/District-Four/PDF_Files/pressreleases2023/166_400Release.pdf

(The Galena Sentinel-Times noted that the traffic switch was delayed from Nov 9 to the morning of Nov 10 due to equipment failure.)

Here is an article containing a letter from the contractor that gives further details:

https://newstalkkzrg.com/2023/11/07/u-s-166-400-east-of-baxter-springs-to-open-this-week/

While for the most part two-way traffic is to run on the eastbound lanes of the in-progress four-lane highway, what I gather from the letter is that at the US 166/400 interchange currently under construction (approx 37.024N 94.7W), both directions of US 166 traffic will use the onramp on the SW side of the interchange.

It's not clear to me from the info available online whether the US 400 bypass of Baxter Springs is open now; if so, it is plausible that both directions of US 400 traffic will utilize the offramp on the W side of the US 166/400 interchange. However, this would need to be confirmed, either visually or by inquiry to KDOT and/or the contractor.