Just reporting back: Covid extension very quick and easy in BKK, Muang Thong Thani Counter K, today - no queue, took 15 minutes in and out. TM30 queue is also very fast, 10 minute way. To return in 2 weeks for another stamp to close the loop. Thanks for the help here. ๐
FYI: to those who don't want to Grab Taxi there as it's in the middle of nowhere, there are mini vans for 36THB outside "Impact" (next to the Novotel Hotel), which is very close to immigration. They leave quite often and take you to Mo Chit BTS/Chatuchak. Vans go to and from here.