What do you mean? I am skipping around a bit and all I have heard is him playing some standard short pieces from classical repertoire (there is no classical stuff as well, no idea if any of this is his composition). I don’t think in most cases those would fit game very well - game OST should first and foremost fit the gameplay and therefore be dynamic and that’s not something you get with prewritten music meant for live performance. Also, game OST tends to be ver passive with little momentum or development - mainly because it is background music with no knowledge of what the player will do. So using music with its own direction and arc would compete with gameplay, not support it. One can compose a more coherent bit of music or main menu, a cutscene or highly scripted event but not a player paced, highly interactive experience.
Unless you mean recording everything on a keyboard and saving music on the orchestra. I dont mind a non traditional ensemble (like string quartet OST to
Arcanum), but I don’t think solo piano would be a good fit for BG3. As far as electric keyboard and samples - the drop in quality from artificial stuff like that is very noticeable. It is a cheaper way of making an OST if you are on the budget, but if you are making a game of a scale no budget of BG3, why not invest in a higher quality OST as well?