If you want Wifi 6, I recommend adding in a ~$18 Intel AX200 m.2 module.
It's at the heart of basically every wifi 6 board on the market right now (Including that TP-link archer afaik), and can probably slot into whatever built-in desktop wifi card you're currently using... if you're willing to do some deep disassembly of it's case and/or heatspreader.
Also it will fit in a laptop.
I agree that these lists are the best and sometimes a small improvement that you use daily beats a big $ upgrade in value.
I just added front USB 3.0 to my 7 year old desktop via a PCIe card ($12) and a 3 foot USB 3.0 cable ($4). I use it daily and the speed increase over USB 2.0 is still satisfying. Got rid of my upgrade urge for a while.
Awesome list. However, you don't need to break the bank or sacrifice fan performance to get that sweet, sweet RGB. You can use Phanteks' Halos and Halos Lux RGB fan frames to place RGB on 120mm and 140mm fans.
Also not mentioned in the article are mouse bungees, which are awesome for removing that "tugging" feeling you sometimes have to deal with when your mouse cable is in a less than ideal position, and external sound cards, which can boost audio performance and quality a great deal, if the people who swear by them are to be believed.
Finally, a good monitor stand or arm is a great option for users who want to face their monitors away from their desks and use them for more than just work or PC gaming.