I don’t know that they are heirloom seeds. They are OP, supposedly.
I was more uncertain about my ability to save them correctly, than the seeds doing their thing correctly.
Saving tomato seeds is simply putting the seed sacs from the tomato into a small jar with a table spoon or two of water and let them ferment for a few days then rinse them off and dry them. All my tomatoes now are heirloom.