It shouldn't come as any surprise that the Protodevlin (primarily, Glavil) and the AFOS resemble each other: they both have the same creator, Kawamori.
both are humongous
both are capable of flight
both are nearly indestructible
both are capable or projecting powerful bio-organic blasts of energy
both are capable of interstellar travel
both are capable of speech
both are, apparently, immortal
both are just plain freaky looking
Actually not Kawamori, but Miyatake.
By the way, did his Design Works book ever come out in the end, or was it just shelved?
Does that mean Agent One is also a creation of Miyatake??
The description also fits him