You should be listening to Brandon. The O and OA are different visas with different requirements. You want the O visa which does not require a background check.
If you were to get a DTV then you cannot have a Thai bank account or you are in danger of losing an existing Thai bank account.
Hospitals often can help with immigration matters. Even if you are home you might ask your doctor if they can help. Doing immigration stuff on time is best but if they can’t help then a letter about your condition may be handy later on. Good luck.
You might want to consider getting a letter from your doctor saying you are unable to travel. If you are in a hospital then they should be able to help you immigration matters.
You will need that 800,000฿ in a Thai bank account to get a 1 year extension of an O visa. You will need it sooner rather than later if you arrive on an O visa. You need to open a bank account that first month to season the 800k for 2 months before applying for the 1 year extension.
People frequently advise those on an OA to do a border bounce to get a 2nd year. You can do a border bounce but you don’t need to do a border bounce. You can extend after 1 year on an OA.
I had an OA for 6 years. I got it before the insurance requirement. I switched to an LTR in 2023. It was helpful to have already had Thai insurance to meet the insurance requirement for the LTR.
These days I recommend the O and not the OA but everyone’s needs and wants are different. Thailand has a lot a visa options but that also makes the visa environment complicated.
I had accident insurance from Kasikorn when I first opened a bank account. It was accident insurance and not comprehensive health insurance. I had an accident a few months later and Kasikorn paid off promptly.