What happens if you sit down outside and eat something he likes, @Summerheadache - no comment or requests for him to come and eat, just you obviously enjoying a treat? Then when/if he comes over say yes, he can have a treat too, when he eats his sandwich.
One thing I found helped when my boys were small was telling them that something I was eating was only for grown-ups, and they shouldn’t like it - it often made them eat it just to prove me wrong.
But I have every sympathy with you - the tantrums of the terrible twos are a nightmare to deal with. I have told this story on here many, many times, but when ds1 was in the worst of the terrible twos, and had been screaming non stop for 45 minutes that morning (after a 90 minute tantrum the night before), and I was on the last shred of my last nerve, I rang dh in tears. As I was talking to him, the screaming stopped, so I rang off and went to investigate, and found ds1 at the kitchen bin, eating left over tortilla chips we had thrown away the night before - and that was what had stopped Thame tantrum. But that isn’t the worst part - I knew that, if I took him away from his delicious bin-snack, he would start screaming again, and I simply couldn’t face it, so I let him carry on until he got bored of the Doritos and wandered off - then I emptied the bin and found somewhere safe to put it.
He didn’t even have the slightest tummy upset as a result - not a bother on him - and he grew up just fine. In fact his best man told the story at his wedding last year!
So don’t worry - this too shall pass.