Obsidian is great; all the files are readable anywhere (easy to migrate out if needed) in a clear, readable directory structure, copying the structure you see in Obsidian itself.
For something like $8/m, you can have their official sync tooling and have it on any devices at the same time, but there are also free options for synchronisation, which require a little work.
You can probably find tools that would migrate your content from Anvil to Obsidian, but also the other way around. There are generally plugins for almost everything; however, there are too many plugins you can use; it's easy to get lost there. Also, as with many other plugin marketplaces, there is no security vetting on the plugins, so you need to be careful.
I wrote an article trying to explain why we as Pagans still matter. It was written for another site, but it closed down in the meantime...
And as there is not much happening here, I decided to post it here.
Obsidian is great; all the files are readable anywhere (easy to migrate out if needed) in a clear, readable directory structure, copying the structure you see in Obsidian itself. For something like $8/m, you can have their official sync tooling and have it on any devices at the same time, but there are also free options for synchronisation, which require a little work. You can probably find tools that would migrate your content from Anvil to Obsidian, but also the other way around. There are generally plugins for almost everything; however, there are too many plugins you can use; it's easy to get lost there. Also, as with many other plugin marketplaces, there is no security vetting on the plugins, so you need to be careful.