The scaling is very simple, how can there be so much discussion?
Cell max is stated by toriyama to be above broly (before you say he wasn't completed, hedo in the movie states that he is completed physically but not mentally so he is still comparable). So cell max, orange piccolo and gohan beast are all "At least low 2-C" and this is the scaling chain:
Gohan beast >> gamma 2 suicide > cell max => broly > orange piccolo.
Next up the gammas. The gammas were stated to be comparable to Goku and vegeta, as of now, goku and vegeta are capped at SSB casually and UI at past the limits. So gammas should at least scale above SSB Goku and Vegeta.
So low 2-C and this scales to the gammas, Super saiyan and ultimage Gohan, base piccolo and potential unleashed piccolo.
And before you say piccolo can't sense Goku and vegeta, he can still sense hikari broly who contest blue Goku and piccolo saw the fight.
He could also sense kefla and somehow sign 1 Goku.