The first 2019 LEGO Ideas Creation to reach 10 000 supporters on LEGO Ideas is Museu Nacional – Rio de Janeiro by MaxakalisaurusTopai. This is the largest Brazilian Museum. Unfortunately, it was heavily damaged by a fire in September 2018. Many historical items were lost as a result.
This creation was created in early January 2019 and it has already reached 10 000 supporters which is outstanding. Congrats! You can find more info regarding this creation here.