@Andrew *******
I’m from the UK but applied for the Non-O visa online whilst in Indonesia. I showed the contract for my local accommodation. I showed bank statements from a UK bank account with equivalent of THB800k. It didn’t need to be seasoned. I don’t normally keep £20k sat in my current account so I just transferred some in so it appeared in my monthly statement and put in back to savings straight away. Took about a week to get it. I came to Thailand and immediately went to a bank and asked what they needed. Then I got AIS postpaid number ( the receipt they provided is essential for bank accounts) I got the landlord to email me the TM30 and took that to immigration. I got 3 certificates of residence (bank accounts, car licence and motorcycle license). Banks took about 30 minutes , they were professional and happy that I had all the documents. I started on Monday morning and by Thursday I had eSIM, accounts at two banks as well as licenses for car and bike. I can see why some people use agents but for me I have plenty of time and quite enjoy the challenge