It's very long to explain in details all the mechanisms involved in an open pollination. I will try my best to be synthetic.
F1 are cemented by the heterosis, the genetic shock when twos "stranger lines" have a meeting lol To do an anthropomorphism, we are all F1 and have the tendency to search a partner able to make F1.
F2 is a repeated sequence, and start to create segregation than start to fight to survive. So you will have specimens more close to the mother than the F1, others more close to the father, other a weak mix of twos with different balances and sometimes also specimens which come from very far, like 4 generations before the initial parents. Depend on the blood in question and if they share a common skeleton (like twos skunks, or two dutch hazes)
When you use an open pollination on F2, you don't backup anything. To don't lost anything, you have to isolate each subgroup then to create a specific F3 line for each subgroup : subgroup "look like daddy", subgroup "look like mommy", subgroup " wtf is this" lol etc ...
So, sorry to debunk this without more words but at this early stage of segregation an open pollination is the more destructive process than can be done. It don't mean than it can be bad at all, who know. But the genetic equilibrium in game will choose for you what to save and what to wipe.