Is ghusl obligatory if a person wakes up from sleep and finds no wetness, but has discharged a thin, white fluid with no odor or desire after manipulating the urethral opening?

What you do to yourself by way of inspecting, delving, and manipulating is from Satan's tampering with you, because the passage of the male organ is often not free from moisture. You are not religiously obligated to extract it, so stop doing that and block Satan's path. What you mostly see is either urine or pre-seminal fluid (madhy), and neither of them necessitates ghusl (definition) (ritual bath); only istinja (definition)' (washing the private parts).