I'm hoping to release pretty much everything needed to run this.
I don't expect it to be easy. The setup isn't exactly straightforward, and the code wasn't designed to be run by others. Someone might make a container or similar to make setup easier, but I'm constantly tweaking the code, meaning that those unfamiliar with it (i.e. everyone except me) are going to face challenges.

How much of the codebase do you think you will be able to open source and how easy would it be to selfhost with some knowledge of linux systems?

Shiru is amazing byt it relies heavily on Animetosho.org unfortunately

These other sites look horrible in comparison. I'll just stick to boozing.

I only found AT recently in the past year even as a relative internet veteran (mid 90s!): Thank you for what you've done for a decade and a half for the whole community. I'll miss AT but thank you for providing such a massive service admin.