You know what this seems to have been only an issue with Brave-beta. Everything else is just working without my manifests. Also, I may have been using the non-beta extension in Chromium at first, which doesn't work with the native app, so I may have mistakenly believed it wasn't working too.
It appears that the 1Password app creates the manifests in the browser config directories it finds on startup. I didn't have Brave installed, but had a config directory lying around from a previous install, and it had the manifest created in the users config directory.
Pinned Comments
1Password commented on 2020-12-17 15:44
Our Linux support discussion is available at https://1password.community/categories/linux-beta
rew1red commented on 2020-09-22 02:40
1Password now signs releases, so signature checking has been added back into the PKGBUILD. If you encounter an error importing their GPG key or an error because of a missing GPG key, you may import it manually:
They've published their key on their support page, here: https://support.1password.com/cs/getting-started-linux/