Pocoyo had many pilot episodes made in Spain in 2004 before the show premiered.
In the pilot episodes, Pocoyo has a yellow pacifier in his mouth, which is something he formerly had in the final series. And also the narrator is an American female in the pilot. This pilot is found, however, there was another pilot which remains partially lost.
UPDATE: A user posted the full music of the second pilot! read this: https://lostmediaarchive.fandom.com/wiki/Pocoyo_(Pilot_Episodes)?commentId=4400000000000048287 the music name is: minimal happy.
While another person posted a rare version of the credits' music: https://web.archive.org/web/20101128221927/http://pocoyo.blogs.com/pocoyo/files/pocoyo.mid
ANOTHER UPDATE: A user posted an early version of the intro music! https://web.archive.org/web/20101128194053/http://pocoyo.blogs.com/pocoyo/files/opening_pocoyo.mid
YET ANOTHER UPDATE: Footage from a possible 3rd pilot was found by Lucio B in this video! https://youtu.be/DRybDRl2IcI?t=12