Wicca is a New Age religion that began in England, so that’s a solid no there.
For Hellenism, it’s historically been incredibly open to other cultures and communities. We have reports of Viking cultures adopting some Greek Gods into their worship. Because of their open history, it’s generally agreed upon that Hellenism is not being ‘appropriated’ by modern worshippers although you’ll always find some people claiming that is somehow is.
I’d argue that anything you think you’ll need, you can put in your BOS. It doesn’t even have to be death-related to help your future self.
But since you asked, I’d personally recommend common symbols on gravestones, books you wish to read in the future, notes on necromancy from different time periods, types of ancestors, different theories on death, and the laws on funerary rights/vulture culture/cemetery laws in your area.
there’s a website where you put in two musicians/artists and it makes a playlist that slowly transitions from one musician’s style of music to the other’s
Variously Backup 