On the subject of "thinking too much about omegaverse worldbuilding" I sometimes think about the historical political ramifications of secondary gender manifestations at puberty (which is often how A/B/O settings arrange things, you get your AGAB and then later on you get classified with your, I guess, ASGAP -- Assigned Secondary Gender at Puberty) (no I didn't set out to call it "ass gap" but I'm keeping it now).
Like if the actual reproductive capabilities of your kid aren't apparent until puberty, that changes the game on a lot of male inheritance preferences, doesn't it? Like maybe your son presents as an Omega and suddenly he can't sire a hundred heirs on a harem of politically expedient wives, you've gotta find someone to impregnate him instead. Or he could, maybe, depending on how the fantasy reproduction works, but it's much longer odds on that.
Conversely, your daughter who would normally be slated for marriage alliances and marrying out presents as an Alpha, and now suddenly she's capable of begetting heirs and less than likely to incubate another family's kids. But you don't know for sure until puberty.
Like a lot of historical nobility traded clout in heirs and arranged matches well before puberty. Sure the kids could still die or turn out to be infertile, but it was a generally safer bet to assume that they wouldn't, and even considered slanderous or bad luck to behave otherwise. And if your son or daughter dies, that just voids any betrothal contracts you might have made, it doesn't necessarily throw them for a loop as it might if, on the other hand, your son who was supposed to marry the viscount's daughter turns out Omega, and the viscount's daughter turns out Alpha, and now you have to renegotiate who marries into whose household, and that's not even the worst case scenario.
Say your son turns out Omega but the other family's daughter is a Beta, and let's say that Omega men can still potentially get others pregnant, but at reduced odds. Do you keep on with the match, knowing that the odds of it yielding children have changed? Or do you cancel it, even though it's still politically advantageous to create that alliance, because without children it's not a better alliance than one with?
Like betrothal contracts all over the world would HAVE to incorporate provisos for this kind of thing. Or else people would just have to hold off on making those plans until after their kids reached puberty. On the one hand that second thing seems like the obviously preferable solution, and also tons of cultures did indeed prefer to handle shit that way anyhow, but on the other hand, with the political nature of marriage matches on the table, there would always be the temptation to take a gamble in order to secure an advantageous connection and then just hope wishin' and a-prayin' would seal the deal.
I think that latter would still happen more often if there were, hrm, further odds involved in anticipating the secondary gender of one's heirs. Like quacks and charlatans claiming that they could predict the outcome well before puberty hits, people coming up with alleged ways of ensuring the desired results, actual odds favoring certain outcomes (i.e. Omega girls being more common than Omega boys type stuff), fortune tellers being like gimme that kid's star chart and I'll tell you what they're more likely to become, and so on.
But also this would open a whole new category of gender shenanigans both real and dubiously verified, I think, like stories of this or that family trying to pass their Alpha daughter off as an Omega bride, or switching around the primary gender to create a more desirable designation (i.e. "no no that's not our Alpha daughter that's clearly our Alpha son"), or families substituting a bastard half-sibling or cousin or some servant's child to fulfill an arranged match's contract because their actual kid came out with the wrong Bonus Gender, and so on. The sort of stories we already have, just dialed up even more.
