In principle you could make your own soundfont, by recording single notes (preferably using a MIDI file to "play" the piano, so you get consistent note-on velocity etc) and using soundfont editor. But the results are unlikely to sound as good as the piano, because you will lose the interaction between sound of different notes played together. Good quality sampled pianos use huge sample sets - for example this one http://www.garritan.com/products/cfx-concert-grand-virtual-piano/, recorded from an acoustic Yamaha concert grand piano, has about 120Gb of samples (and even the "lite" version is about 20Gb).
Note, making a soundfont this way may not be legal - check what the user licence agreement for your Yamaha says about "reverse engineering."
A different computer simulation method creates a mathematical model of how the piano actually "works", rather than attempting to recording every possible sound it can make. Software like https://www.pianoteq.com/, which uses this "physical modelling" approach, needs much less memory and disk space than a sample library, but uses more CPU power to generate the audio in real time as you play. Any modern computer (including laptops) should be powerful enough to run it.