Standing desk with memory, not the ones with just the up-down buttons. I can just slap number 2 on the desk, push back and stand up. The table will stop exactly at my standing work position.
Walking mat for said standing desk. A coworker of mine swears by this, I'm still considering one. They even walk while watching movies on the TV :D
A proper working chair, your ass is going to be on it for 8+ hours. Don't skimp on it.
Steam Deck. Seriously. It made gaming fun again. My gaming PC hasn't been booted since September when I got the deck. I can only do one thing with it, play games. It's always suspended on exactly where I left with the game I'm currently playing through. I can use it on the couch, toilet, train, vacation or even when there is downtime at work =)