You can create a project which still includes the WAV samples, so people can customize it further or use the samples for other things. Roland Kuit did this for the Old Skool Drums he created and which you can find on on the Nord website in the Sample Library.
Other than creating your own multi sample (nsmp) using the Nord Sample Editor I don't really see a way to do this. I previously had a look at this, but Clavia uses a proprietary algorithm for the (lossless) compression; they either developed that themselves (and probably consider it a trade secret) or licensed it from some other company (in which case it is very likely they're not allowed to divulge any details on how it works).
But as long as you only need one sample per key, you're good to go. Convert your samples to 16-bit 44.1 KHz WAV files (other formats might work, but I haven't tried it) and start dropping them in the Sample Editor. If you get clever with the naming, you won't have to do much tweaking and in that case it isn't actually that time consuming.
For example, I sampled a toy piano and gave the samples names like this:
- piano-c3.wav
- piano-f3#.wav
- piano-c4.wav
- piano-f4#.wav
I used just two samples per octave, which is often enough. I'm pretty sure you can also use MIDI note numbers in the file names, so instead of piano-c3.wav I also could've named the file piano-48.wav and I should've gotten the same result. Just load a whole bunch of samples (with names like this) and they should be mapped out across the keyboard automatically.
If you use samples of different instruments, sound effects, etc. and don't want a 'fade' from one sample to another (i.e. c to f# in my case), make sure to place samples at the 'edges'. For example, if I wanted c2 to b3 to be a toy piano and c3 to b4 to use a bell-like sound, I would place the toy piano samples at c2, f2 (or f2#) and b3 and place the samples of the bell-like sound at c3, f3 (or f3#) and b4. I hope this makes sense.
You can of course use a separate sample for every key if you want to, but generally 2-3 (as mentioned above) is enough. This makes for even smaller samples.