Essentially that's correct. Heirloom specifically refers to older style or rare varieties not really seen in large scale commercial production. But NON-Hybrid is the key. What you want is something the will reliably reproduce. Hybrids don't.
If I may suggest the following book tells you how to harvest and store those seeds.
“Seed to Seed” by Suzanne Ashworth.
Also a correction. In the previous post “Frost Freeze”, should be Frost Free. You want to get a dedicated freezer that gets to at least 0 degrees F. This can extend the seeds by virility by years.
Excellent. Thanks. I’m gathering all this info together. When the SHTF, we may well have to rely on a network of outposts where we can count on each other.