I am using the Contour Unimouse at work. Very customizable to your needs. I only find the choice for default button assignment a bit weird - it has 3 buttons + mouse wheel on top and the middle button has the same action assigned as the mouse wheel “button”. Due to the size of the mouse and buttons I have the middle finger resting on the middle mouse button whereas on other mice the middle finger rests on the right mouse button. So you’ll need to use their (not so great) software to change the button bindings. Other than that a very robust mouse with high customizability.
I am using the Contour Unimouse at work. Very customizable to your needs. I only find the choice for default button assignment a bit weird - it has 3 buttons + mouse wheel on top and the middle button has the same action assigned as the mouse wheel “button”. Due to the size of the mouse and buttons I have the middle finger resting on the middle mouse button whereas on other mice the middle finger rests on the right mouse button. So you’ll need to use their (not so great) software to change the button bindings. Other than that a very robust mouse with high customizability.