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I got this one for my partner before surgery just in case--she used it, but not super often. Would generally sit on it for a little bit, change positions, move it out of the way, sit on it again, etc. I think she would have used it more if her surgery hadn't been right before lockdowns started (March 5th was her surgery date)--she's been working at home since, and spent the better part of a month working from bed/laying on the couch, but if she'd gone back to the office she would've brought it. I think there's no harm in buying one even if you aren't certain you'll use it, just because it's easier to stock up ahead of time. Good luck!!
with my first pregnancy, I bought a donut pillow like this that helped. I had a lot of tailbone pain and sitting was really uncomfortable. The pillow helped a ton, and wasn't a super expensive buy. Also, if you're at a bigger company, you can ask for an ergonomics assessment to see if you can get a sit/stand desk or try getting a big yoga ball to sit on.