The relevant frameworks and criteria really are commercial rather than legal. Crossing the line of “what will get us banned from the Apple Store” is much more relevant to CoG, has been for a decade, and will be for the foreseeable future. Whatever porn wars some of MAGA’s sweatier fringes may try to fight, they’re not going to get to the point where it’s any threat to erotic novels – that would just be a dumb place to start (and very rapidly lose) the fight.
I don’t know if you’re ready to let yourself be reassured by any of that… but there are a lot more imminent threats to the Constitution than book or porn bans, and it’s worth keeping our eye on those rather than trying to find (or dream up) examples of the chilling effect of Iowa’s law on non-school libraries.