You mean a sit-stand desk. There pretty neat. If you can get the whole proper desk. Not just the risers that sit on a normal desk. There prone to cutting csbles, monitors falling and just take up space.
I think the point with standing desks is really you just want one that can convert to either be a standing or a sitting desk. And you switch it up from time to time.
It's odd the people that advocate for standing only all day. Standing in one spot all day is straight up painful unless you've got a nice standing mat. Even then it can suck. Walking all day is different and won't hurt as much. Long periods of immobility in any position aren't exactly great for you, whether you're sitting or standing. Not having the option to sit is also terrible.
A combo of standing and sitting is best, not one or the other.
All the obvious ones have been mentioned already, so I'll just add:
Keyboard tray if your desk doesn't have one. It allows you to achieve the 90 degree arm position without having to set your desk too low or your chair too high.
Wrist pad. A nice gel pad provides great support for your wrist. Just make sure your keyboard and mouse are at the appropriate heights, because if not, a wrist pad can make it worse.
Head rest add-on to your chair if it doesn't have one.
Laptop stand to lift your laptop screen to eye level. It also helps to keep it aligned to an external monitor so they are the same heights.
A good chair that is the proper height and adjustable.
Adjustable height monitor supports.
Ergonomics is all about geometry. Most of the problems people try to fix w8th wrist supports or ergonomic keyboards are really problems with sitting too high or too low in comparison to the keyboard and/or monitors.
The ability to raise and lower the chair, the desk, and the monitors independently will make a world of difference.
I might also add that some people forget about the "repetitive" in Repetitive Stress Injury. Adjustable is your friend because it allows you to find a really good posture, and also because it allows you to accommodate multiple postures through a day or month or whatever.
I recently got a Therapod chair and it's the greatest thing I've ever sat in. It has adjustable tension straps built in so you can make the lumbar support exactly where you need it.