I have a 10a and I'm debating between lineage and graphene. Does anyone have an opinion on which is the better option these days?

If you live in the US, Graphene (because fascism).

Also, I'd go for Graphene anyway just because it's easier to install and I don't know of any particular killer features Lineage has that Graphene doesn't (other than working on many more devices, which isn't relevant to you).

I used lineage on 3 different phones for several years back in the day and always liked it but the security of Graphene is really the main reason I'm considering it. I think I'll give it a go on my old pixel 6 first and see if it suits me.

The two OSs have a completely different purpose and approach to privacy.

Lineage OS= Degoogling while keeping android compatibility.

Graphene= Actual privacy via individual security context for each app.

to expand a little. I'm actually on the market for a 10pro because de-googling has not been enough for me.

Android's native permission system is broken and google refuses to fix it. Many many apps (Facebook, aliexpress, instagram) reach outside of it's own environment to read other apps

Currently I'm using "Islands" as a workaround. (Highly recommend it)
https://f-droid.org/en/packages/com.oasisfeng.island.fdroid/

Graphene fixes this permanently by allowing you to set specific permissions for each app to access only it's own files or otherwise allow it to access others on a one by one basis.

Thank you this is a really good explanation. I'll definitely try Graphene.