I can confirm that Pattaya City Hospital, Soi Bukhao, has a Pfizer vaccine booster shot available on Fridays between 9:00 and 12:00 p.m.
Don't forget to take your passport. I was able to show them a picture of the main passport page and use my Thai driver's licence.
Also I don't know if it's required but I think out of respect you should wear a mask while in the hospital.
You have to register at the desk shown below in the picture. They will give you a registration form to complete which is only available in Thai. I will also include a screenshot of Google lens translate of the form which may be of some help.
When complete take it back to the same desk and they will enter your data into the system. Then take a seat and wait. This should only take 5 minutes and then they will give you back your form and you will be instructed to go to the 5th floor for your injection.
When a nurse is available just give them your registration form and wait to be called up for your injection.
The whole process took less than about 30 minutes and I arrived about 10:45 a.m.
I didn't enquire if any other injection types were available or if you were able to get your first or second injection.