You can use text object and then use snap to face or face project snapping to place them on the keys. I’d recommend using the text editor to type out all the letter and as many of the symbols as you can. Put one per line. then click Edit->Text to 3D->object per line. You can change the font as you see fit. For the named keys like Num Lock you can do as one line then after the text object is created you can edit it by tabbing into edit mode and then add the return to make it double lined. For symbols like the arrow keys you can choose a symbol based font like windings or if the font you plan on using has a special character you can use a word processor text editor and insert the special character in that program then copy(CTRL+C) and paste(Ctrl+V) in Blender’s text editor. You could also just create it using curves or a mesh. Another option is to find an SVG of the keys faces. Usually they just have the keyboard layout.
