In preferences keymap under 3D View you will see the Grave Accent/Tilde Action. Navigate needs to be highlighted for the view pie menu to show up. If you are getting a Move, rotate, scale pie menu then that mean you have Gizmos selected. If you are being put into a walk/Fly mode then you have Pie Menu on Drag checked. In which case to get the pie just hold the tilde down and move your mouse or you can uncheck that option.
And if you hold ALT+MMB and 'swipe' up, down, left or right, you switch to the Orthographic Modes: Bottom, Back, Top, Front, Right and Left, with the additional bonus of being able to get into a 'rotated' Top and Bottom View. For instance, if you first 'swipe' right (with ALT+MMB) and then down, you get this:
This is harder to do with the NUMPAD keys (default would be with NUMPAD 7 followed by 6 times NUMPAD 4).
And of course, this doesn't work if you have Emulate 3 Button Mouse enabled.