@Tara *********
You will have to see next week so far no announcements been made to allow you to travel domestically before completing the one day "test & go" as they are calling it.
As far as airlines allowing you to book tickets they will let you book, they will have a disclaimer somewhere hidden in document thats its your responsibilty to check regulations. Seen it many times since this covid travel started and then its a pain trying to get refund.
They do have ASQ in Chiang Mai already I think its for people who come overland or have the luxury of private jets.