hmmm… It’s been a while since I have looked at it, but Foulplay should save it’s current pattern state on exit. Pattern state being the number of steps, fill, rotation, probability, trigger logic, and mute state per track.
To save your loaded samples, you’ll still need to use the parameter menu. Navigate to Parameters, then hold key1 to see the save/load screen.
FWIW, I did it this way so that you can load patterns and sample sets independently, from the grid interface. this allows for swapping samples while the pattern keeps playing.