There is not a way around it. You need to be in your Home country to apply for the DTV. You cannot be in Thailand and you need to prove that you have 500,000 baht in a Bank in your home country for the last three months there is no way around that. And no agent can help you with the money portion. An agent can help you apply for the visa, but it’s not necessary. It’s such a simple process.
DTV is a nomad visa, you have to show That You are working remotely. It’s not a retirement visa, but the Thai visa website explains things Fairly clear.
the first response you had you said on the DTV you only had to show your bank statement from America. We’re talking about getting bank accounts in Thailand on the tourist visa he’s not talking about getting the DTV visa he’s talking about getting a Thai bank account on the tourist visa
in Thailand. Only businesses have checks from my understanding. Personal people do not have checking accounts. Just debit cards. And transactions from phone app
you have to set up with the Bangkok BANK. The amount that you are allowed to transfer 50,000 is the standard if you want to do up to  200,000. You have to process it through your branch and they will take a picture of you and your passport send to Bangkok headquarters and verify and then you will be able to to do 200,000.
You can buy unlocked phones on Amazon and use a AIS Sim card keeping it only for Thai phone number and operates off Wi-Fi without any service provider and you are fine