I can imagine, so DECLARE command will be introduced as short cut for CREATE TEMP VARIABLE, but in this moment I would not to open this topic. I afraid of bikeshedding and I hope so CREATE TEMP VAR is anough.
Language is important because language stays.
You choice of syntax will outlive your code and possibly yourself.
sure. But in this moment I don't see difference between DECLARE VARIABLE and CREATE TEMP VARIABLE different than "TEMP" keyword.