Hi @aroeira, glad to hear it’s working for you – except for the codecs. Which version of the snap are you using (revision + channel), and on which architecture?
Thanks @alan_g for the ping 
EDIT:
I just tested wpe-webkit-mir-kiosk on a Raspberry Pi (armhf) running Ubuntu Core, WPE snap from latest/stable: 2.30.5 / rev 56
Audio codecs all show “Yes” except Dolby Digital and Dolby Digital Plus, video codecs all “Yes” except H.265.