Your right hand will not be quite well prepared. It's more like your key-finding head is somewhat prepared. The piano keyboard is not as much velocity-sensitive as it is momentum-sensitive: you need to transfer a certain momentum in order to arrive at a certain loudness (unweighted or "semi-weighted" velocity-sensitive keyboards are not really an adequate approximation).
So the next articulatory relative is rather a harmonium, followed by an organ. The difference between the two is the complete rather than partial loss of bellows control as well as a bunch of "real" mechanics attached to the keys giving somewhat more inertia to the keys.
As you change from wind instrument to momentum-controlled percussive instrument (the harpsichord is percussive but the attack strength is fixed and the key sounds once you pass its counterforce), the importance of the release timing of a key decreases while the importance of good momentum control comes into play. That's where the typical piano keyboard offers a better mechanical interface than a chromatic button accordion keyboard, at the price of taking up considerably more space and weight. It also means that the high importance of "legato fingerings" decreases and instead it becomes more important to find fingerings that give each finger sufficient movement freedom to strike with controlled force.
With an accordion, your finger action is basically self-contained and no significant amount of energy transfers permanently to the keys. With a piano keyboard, all of the produced sound energy comes from your playing fingers rather than an independent bellows.
Once you pass the threshold from merely sounding notes to actual articulated and expressive play, the piano and the accordion become significantly different.
So I'd focus on scales and stuff and try getting consistent articulation (staccato/leggiero/legato) and controlled crescendi/decrescendi, also when playing long runs with alternating hands.
