Saving Sunflower Seeds

I'm having trouble finding good information like I can get for vegetables, for flower seed saving. For sunflowers, are they self pollinating? Is there a minimum plant requirement? Isolation distance from other sunflowers? And maybe this is a stupid question, but for a pollenless hybrid, is there still a chance there's some pollen available and it could cross-pollinate with an open-pollinated sunflower?(Điện hoa hà nội) We grow hybrid cut sunflowers at our farm and would also like to grow sunflowers for seed (bird seed, human seed and some for planting next year), but I can't find much literature on this crop for best practices.

Usually the birds eat em all if you dont cover them lol, use fabric to cover the heads that can let the air and moisture through like the shade cloth thats breathable. Then cut the heads down about six inches when they start to turn brown and hang them or leave them on a drying rack until the seeds fall out easily. Non hybrids are going to be the best bet for seed saving for planting next season.

this phrase in Google yielded many informative sites:

Helianthus biology reproduction pollination