I admit I am coming late to the party on this one, still as I have a couple of Sigma super zooms: the 150-600c (I suspect the OP may have the s version, given the weight indicated), and the 60-600s which is significantly heavier.
I use these lenses predominantly with the Canon EOS 7DII, 90D, and R6 bodies (the latter with the adaptor). In terms of carrying the lenses I prefer to carry the leans across my torso (as one does with a rifle), supported on both arms. I avoid any straps that put a lot of strain on the neck, but I have been known to use a belt with a clip or sling unit to take the load. I have, on occasion, used a monopod for times when I expect to be relatively static, but most of the time I am shooting hand-held.
For that reason I specifically do weight-lifting to make sure I have the muscular strength and endurance to handle the lenses. Like every endeavour, training to improve one's performance (be it intellectual, proprioceptive, or endurance-wise) training pays off.