If I get an O-A visa in my home country, I know that I will have to go and do a 90 day check-in. When I do the check-in will immigration check if I have a bank account and if I have 800K in that account?
TLDR : Answer Summary
During the 90-day check-in for an O-A visa in Thailand, immigration does not check your bank account or verify the 800,000 THB requirement. You simply need to report that you are in the country for 90 days.