@John *********
You said "Much better doing it yourself than using an agent that can lead to issues down the line".
I can spell out what the issues will be if someone had used an agency. The agency would get you a fully legal 1 year extension Non -O visa.
The caveat is : agency would make your TM30 at the adrress you would not even know where it is. The Visa would be legally issued and stamped in your passport from some Immigration office in a far flung province. All OK.
It is legal, I enterend Thai on it 29. October 2025. on Non-O visa 1 year from an agency that charged me 34,000 THB.
Then, renewal. Your address (TM30) may well be different now if you have it at all (if you had used an agency and live elsewhere, not in a province/address you may hardly know where it is), Immigration would refuse to extend your 1 year stay until you sort it out.
Now, that I have everything sorted out, Yellow Book, Thai ID, Thai Driving Licence, TM30 for my home that I own in Bangkok, a new bank account that I opened with Kasikorn bank, I might even use that agency to do the leg work upon the renewal of my 1 year extension stay in Thai. It would not be THAT expensive.