Got my 60 days Covid visa extension today at Nan Immigration. I got 2 stamps closed within the same day application.
Moved from Bkk to Nan so I had to file a new TM.30. Was asked to provide embassy letter and the usual extension forms TM.7 + STM.2 (they prefer their own forms so don't bother to print out a downloaded version) copies of passport ID page, latest visa stamp, TM.6
Not a very busy office I would say, feel free to walk-in. No need to set an online appointment.