Thanksgiving

You are correct that Liberty Tree Tavern at MK does a Thanksgiving Dinner. I have also read that most of the TS restaurants will offer a thanksgiving type meal on/around the holiday and that they just don't get added to the Thanksgiving list that Disney puts out.

Places I have read where people have enjoyed a good Thanksgiving dinner:
Liberty Tree Tavern at MK
Whispering Canyon Cafe at WL
Garden Grill at Epcot (The Land)
Hollywood & Vine at HS (buffet)
50's Prime Time Cafe at HS
Wine George Bar at DS
Boma at AKL
Rose & Crown at Epcot
Trail's End at FW

As far as being there on Thanksgiving, I have never been there on Thanksgiving. Crowds obvious vary as I heard one say that at MK T-Day 2017 was low crowds but 2018 was really crowded so they went to AK which had low crowds.

Last year my wife and I enjoyed our first Thanksgiving at WDW, this was entirely different for us, our first time not cooking a turkey dinner.
We thought how lucky we were to obtain a reservation at Liberty Tree Tavern in the MK on the day before Thanksgiving.
Previous dinners there were always fantastic, but this day we really did not enjoy it. Could have been the crowded room or the crowded park that didn't help the food which was only okay, the server was less so.
Thanksgiving Day we had reservations at Rose and Crown in EPCOT for their traditional dinner. We sat out by the water in the shade, it was a warm day and the food was fantastic. The server was also a blessing. Everything was delicious and the desert was a pumpkin cheesecake.
We highly recommend Rose and Crown for Thanksgiving if anyone gets the chance in the future.
Also, the Earl of Sandwich has a great hot turkey sandwich at the Marketplace. That day we actually brought one back to our room for later.