OK, as the geeks are staying home more and more, it's way more important to have the right working environment and to make sure it is ergonomic and not going to give you Carpal Tunnel syndrome or neck aches. So here are some notes on things to get in order of importance (at last IMHO):

1. Chairs but most important posture. While I've always wanted a $800 Herman Miller Aeron chair, the truth is that, at least for me, the main thing is to get something adjustable so that it can be as high as possible and (sadly) to sit on the very edge of the chair with a straight back. I have an exercise ball to sit on as well (but haven't filled it). The main thing is posture, posture, posture. 2. AmazonBasics Monitor Arm, or Dual Arm. Ok, this is going to sound pretty weird, but most monitors are too high or too low. You don't want to look too far up or down and with a basic 27", 32" or even 40 or 43" monitor, this$116 does the trick. One of the nicest cheap setups are a pair of 27" monitors on the dual-arm, so you can position them with a working section and a non-working one for the display of other stuff.
3. Splurge on a great monitor in 32" or even the LG CX 55" monitor. I have not yet found a monitor arm that can swing such a big monitor around. But if you really compute all day, there is nothing like the LG CX (the BX has 500 nits vs 650 nits brightness). As an aside, don't bother with a 4K monitor at 27" you really won't see the difference. You need to sit very close. Rtings.com has a great analysis of this taking into account the human eye's ability to resolve and typical field of view for watching a movie. But that isn't what you do with a monitor where you zoom in on a section. I usually divide my monitor into four quadrants (six if it is 43" or larger).
4. Color correcting your monitor. OK, this is nerdy, but don't just make your monitor blazing white out of the box it's super fatiguing. So if you print, then the Datacolor SpyderX Studio is $500 but worth it to get your printer to look great. The alternative is that you can use the X-Rite i1Studio which is two gadgets in one, it does both printer and monitor at the same time also for$500. And if you are never going to print, but just want the colors not to be too horrible, then the Datacolor SpyderX Elite at $219 is a good choice. You can save$50 if you use it with the shareware DisplayCal since the Datacolor SpyderX Pro at $180 uses the same hardware. The X-Rite i1 Display Pro is another great one that is very fast although expensive at$320.
5. Switch to dark mode (for free!). Safari doesn't do it, but Firefox and Chrome have free dark mode extensions that fix this for most websites. Make sure your terminals us Solarized Dark. I've found that to be a great color for monitors. Having at your office this handy $170 DataColor will really make things feel more pleasing. 6. A great (coder) keyboard like the Varmilo (straight from Shenzhen). Ok, you are typing so much, you really want a great one. Now while you can get a gaudy gaming keyboard with LED lights (I have three!) like the Corsair K95, when you are coding or mainly typing, you want something small and compact. The mechanical keyboards really have a great feel. While I've used WASD CODE as my goto keyboard, right now Wirecutter used to love those, but now at Mechanical Keyboards, they favor niche brands like Varmilo or Ducky (from Taiwan). These all use CherryMX keys and at$125, you can even get a variant VA-87M for Mac that doesn't require changing the modifier for Mac or a Sakura which is in cool pink.
7. Pick the right key switch. Personally, I like the audible feedback and click, so getting a high-quality Cherry MX switch is important. I like the MX Brown or get the classic MX Blue. I really like the so-called 87-key keyboards. The larger ones are called 104-key system.
8. A great wireless mouse. There are many of these as PC Magazine can testify, but the Corsair Dark RGB Pro SE is one of the few that uses a standard Qi charger so it is way more convenient and standard. Expensive at $80, but worth it if you are using a mouse a lot. 9. An amazing Qi charger plus mousepad or just a great gaming mousepad (thanks IGN and PC Gamer!) There are two choices here. You can spring for a Qi charger integrated into your mouse pad. Or if you want to be really luxurious, get this$80 Japanese mouse pad Artisan Shidenkai Ninja that is soft but has "glass" crystals on top so that it has a little resistance as a hard mousepad. Personally, I love the hard pads because there is no rolling resistance. Corsair MM1000Q while crazy expensive at $79 is one of the few hard mousepads with a Qi Charger in it. Or the Logitech G440 is a much cheaper simpler hard mousepad. 10. Wrist rest at Tech Guided or Lifewire. Well, the last piece to make sure that when you type, your arms are level, so you actually want your keyboard a foot into your desk and the monitor over it (thank you monitor arm!). Then the next thing is a wrist rest to make sure your wrists are not unnaturally high, your fingers should actually "float" above your keyboard. The HyperX is a good example of a simple$20 long last product that is made in a gel form. The Gimar is made of foam as is the Glorious Gaming. The nice thing about the Gamer is that it comes in shorter sizes that work for 87 keyboards.