If you want something minimalist I can recommend the HÅG Capisco. It looks a little bit weird, but is really comfy once you get used to it. The chair supports active sitting which means you won’t sit in one position for eight hours straight, instead the chair will invite you to move around and try out other seating positions which will inevitably lead to more movement and stronger muscles.
https://store.flokk.com/us/en-gb/products/hag-capisco?store=...