If you want keys not buttons then try the Melodica (Pianica). A popular childrens toy instrument back in the day. I doubt whether Bryan will have time to read up on L'Accordinas as I understand his current project, the Cajun Calliope, has design issues.
A melodica is far from sounding as good as an accordina. More like a toy, as you say (my parents always wished they had not bought me one when I was a child ).
The original Accordina was invented by BOREL of France in the late 40's early 50's.
The keyboards arte closely related to the continental chromatic accordeons or CBA Chromatic Button Accordeon.
Wood ones are made by Laurent Jarry and others but the best are still in the metal style of the BOREL made by Marcel Dreux in So France.
They come in CBA 3 row or fully diatonic three row or with piano keys.
Unlike the harmonica, the accordina is blow only no draw.
They run about $1500-$2000 USD
To my ear.. in the posted videos the first one flat sucked... Galliano is Galliano...very fine accordionist and one of my favorites.... and the Japanese guy wins the prize though his rhythm guitarist is clueless, she tries to get the Gypsy Jazz beat and vibe , but no cigar. Great music though and the accordina gets it all the way. Very expressive.
Professional chromatic harmonicas with 16 holes have about the same range and have their own special sound and style of play.