Last Updated May 10th, 2024. Still working on updating some of the images and gifs.
I have found a fix for the cl_quickinventory_filename command, I uploaded a video here explaining how to properly change your weapon wheel (this fixes the black circle issue, and config not loading). If the video sets itself to 360p then change the video resolution - I don't know why it does that.

If you don't have the default radial_quickinventory.txt in Counter-Strike Global Offensive/csgo, or messed up your default file go from here: https://pastebin.com/27nsDWMu and create a radial_quickinventory file, and follow the steps from Customization.

In your controls, find the Radial Weapon Menu bind. In the console it is the command "+quickinv".
It by default binds to Q. In the settings, it says that tapping it acts as a quick-switch bind, but I haven't gotten that to work.

Hold down the key/mouse button that you bound the radial weapon menu to will bring up a circular menu (see gif below). Move your mouse towards the item that you want to equip. Note that you do not have to click to choose a certain item, so be careful that accidentally pressing the bind may end up making you swap to something you don't want, and end up getting you killed. The default look of the radial weapon wheel is kind of unusuable in my opinion, and it probably turns a lot of people away from using it. Fortunately, there's a way to customize it.

This is confusing, but if you follow exactly step by step, it will make sense. First, find the radial_quickinventory.txt file in your Counter-Strike Global Offensive/csgo/ folder (or if you don't have it, here's a pastebin copy: https://pastebin.com/27nsDWMu), and make a backup (copy of it).

Next, rename your file to something unique, and easy to remember, like radial_quickinventorycs2.txt, or newradial.txt

Next, copy your file to Counter-Strike Global Offensive/game/csgo - the reason you need to do this is because the directory that cl_quickinventory_filename pulls from is /game/csgo. Once you've done this, we can begin customizing your radial menu.

to apply your config, do cl_quickinventory_filename "yourfilenamegoeshere".txt

This should be what your file looks like.

The Top Slot is what you want at the top of the radial weapon wheel.

The rotational offset is how much of an angle you want the wheel to be at.

Wedge weight is how much of the wheel you want certain icons to take up, i.e if you want Rifle to be larger than grenades put it at 3.0 and grenades at 1.0.

Valid slot names is self-explanatory.

Individual Items works like wedge weight, but on a per-item basis.

If I wanted to make a radial wheel just for grenades I would remove everything that does not have two slash marks (commented out) from the TOP SLOT and the SLOT NAME sections - next uncomment the individual items, so you are left with just the nades. You next need to reorder it so that it goes Molly, Decoy, Flash, HE, and Smoke. Next, add MELEE (in the same format as the other items on the list) to the bottom. Last, set the rotational offset to 300

If you did everything correctly, it should show up like this:
It should look just like the grenade buymenu.

The nice thing about the Radial Weapon Menu is that the changes you make to the config show up with out you having to restart the game, so you can tweak it with the game open.

It is a bit finnicky, so you won't notice immediate changes while ingame sometimes, you may have to leave and rejoin a game session sometimes for your config to take effect.

You're probably wondering, why not just use the grenades preset? Because that offers less customization of each individual grenade slot, and instead you could have the flashbang slot be larger compared to the smoke slot or he slot, and you could also do something interesting like a 90 degree nade setup (rotational_offset set to 45, reordered to HE, Smoke, Molly, Flash):
Or include a little slot next smokes for the decoys for breaking windows (same config, but decoy goes between Smoke and Molly and change the weight of every item besides decoy to 7):

If radial weapon wheel shows up as black circle with nothing inside, do the following:
make sure that your file name has .txt at the end (i.e if it is called myradialconfig you don't have cl_quickinventory_filename myradialconfig, instead it would be
cl_quickinventory_filename myradialconfig.txt
If it still shows up as black circle, do the following:
make sure your files are in game/csgo
verify integrity of game cache
make another copy of the radial_quickinventory and put it into game/csgo and test that before you start editing
have copies in both
Counter-Strike Global Offensive/csgo and Counter-Strike Global Offensive/game/csgo

There are two new radial weapon wheels added in CS2 if none of these work that require no radial weapon wheel config file
+quickgrenaderadial
+quickbuyradial

The Radial Weapon Menu can be used in a number of ways, but I personally think it is an good alternative to using the scroll wheel, spamming four to swap through grenades, or using individual binds.

You don't have to use it specifically for grenades, it can be whatever you want it to be.

The Radial Weapon Wheel was released on April 30th, 2019.

Questions? Comment down below.

Thanks for reading through my guide.