Although I never used it, I am aware that Calibre can serve books in your local network. I imagine that this offers some position and annotation sync.
Also, a bit off-topic for this sub, but… how do you read? E-readers? Tablets? Software choices?
Unfortunately, there was never great ebook hardware. I use a tablet with Android. KOReader for ePub, constantly trying new Android PDF readers but finding nothing decent.
While not intentionally, running Syncthing between all my computers means that my PDF annotations get synced across devices. ePub ones do not; afaik KOReader uses its own metadata format that it stores as a standalone file.
Before, when I was still in university, I used Zotero also for annotation management. Feels like an overkill nowadays since I only read for leisure.
I dunno, I'm still not comfortable with with linking human queerness with biologism and the natural argument. Other animals also regularly do unsavoury things and those urges might still exist in our biological programming but we have reasoned our way of them them.
I don't want to accidentally make strange bedfellows with other groups who point at animal behaviours to justify their problematic shit. Such studies on animal sexuality should stay a matter of science, the queer movement should not take them on as political arguments.