You can find information in the following forum thread. It’s in Russian so you’ll need a translator, and to download certain files you’ll need an account. However it offers both official and unofficial tools and instructions to bypass certain things to unlock it, might help you.

https://4pda.to/forum/index.php?showtopic=721838

Most, but there are exceptions, mainly the messages app, calculator, phone app, and keyboard that I know for sure.

Yep, they put in a lot of effort into the security and open source stuff, but at least on Graphene, the bundled apps are severely outdated aosp apps, they don’t even support material you, meanwhile current aosp apps do support it, as can be seen on Lineage. The calculator app looks straight from Android 5 or probably earlier.

I’m not sure but afaik CalyxOS and LMODroid does that.

Most of the time I find this stuff on 4pda. Sure it’s in Russian and it requires an account to download files, but they delve much deeper into the device and usually you’ll find working instructions how to unbrick stuff.

I never knew exhentai servers are in moldova, and I live in moldova