No replies from knowledgeable people?

I'll do my pitiful best:

There've been threads about growing cannas from seed in the past, so you might do a search to find them for detailed info.

You have to scarify the seeds (crack the hard outer layer) & then put them in a glass of water until they sprout.

Many times the resulting plants will be more "species" type (narrower, pointier flowers) than the hybrids from which the seeds were harvested, but you just never know: you might get a whole new type.

I never had any luck:
the seeds were so hard to scarify that a friend's husband had to do it for me, & then they all rotted in the water.

Since cannas are readily available here, I never tried again, but growing them from seed does hold a mystique.

Best luck!