My hot take is that short-term posture doesn’t matter all that much. If you have bad posture but you get up every 20 minutes and stretch/do chores/exercise for 5-10 minutes, you probably erase the original issues.
My one-two punch, if you’re looking for advice: make sure you use a chair that makes good posture easy, with your keyboard+mouse & monitor height well separated on your desk (if computing’s the main thing you’re doing as you work). And then make sure you’re getting a lot of activity throughout the day. Spans of 2, 3, 4, etc. hours just sitting at your desk will be really bad for you, no matter how good your posture is.
I guess what I’m saying is if you can either focus a lot on posture or focus a lot on physical activity routines, prioritize the latter. But both are certainly important.
Portland, Maine…just in case it’s not clear. (Wasn’t to me until I poked around the website a bit.)