Really fun game! Controls are a bit clunky. You might want to use Input.is_action_pressed() instead of Input.is_action_just_pressed if you did it that way. I love how you can mess with another player by guessing what word they are trying to make and stealing all the Ns for example. Honestly this fits arcade so well it should be in an arcade.
However I have a few nitpicks.
Controls and how to play are unclear.
Here is some instructions for the time being if there is somebody wondering how to play:
Move with Player1: WASD and space Player2: arrowkeys and enterkey
you can make words with any thing. they don't have to be right next to each other.
press space/enter over a blank tile to send your word.
Might edit in more later.