That sucks. Welcome to the show.
Unfortunately you named the only things it could be.
You mention the carb is jetted, but have you cleaned the carburetor idle jet passages individually since your last attempt at starting?
Fuel getting to the intake? If you lay the bike on it's side, the carb should overflow and leak on the ground. If you are unable to flood the carburetor in this fashion, no fuel is likely getting into the intake. what happens with starting fluid sprayed down it's gullet?
What color spark are you getting from the spark plug?
You measured compression at what psi? What percentage did a leakdown test show as far as valve/ring health?
What did you do to 'check timing?'
I ride a 110 4T every single day to the mailbox. It has no air filter. Unknown amounts of oil. Never been changed. motor is absolutely covered in sand.
Never one starting issue since Timo gave it to me. They are impossible to kill, so your issue is probably an easy fix.
-BIG DAN