Thats been my theory for a while tbh! Never thought about the Laboon parallel but damn! I thought it was the last living dragon tbh, a Western type dragon like the one Zoro killed at Punk Hazard, well that one was a clone ofc lol.
Celestial Dragons, Monkey D Dragon. I genuinely believe Dragons existed in OP, well they obviously do as we know from that dragon and Kaidos fruit ofc but we've yet to see living versions of either dragons too. Spirited Away had a young boy who turned into a giant Japanese dragon, sound familiar?
Dragons love hoarding treasure and hiding in dens (lol Den Den), like Smaug for example too ofc. A dragon guarding the One Piece directly maybe?
Oh look btw, its Germa!
And for my final (Ghost) Trick!: