Great ideas! Searchable block lists should be very simple to add. Actually I thought I had already added support for this, but I was mistaken.
For viewing blocked content on the other hand, this will take a bit more work. Lemmy does not return any content for users or communities that are blocked, so I'll need to add support for viewing them as a guest. I'll have to look into this one, as currently Arctic is not setup for viewing individual pages as an unauthenticated user. In the meantime for a quick release I could allow opening the communities and profiles in the browser.
I'm in the process of rewriting Arctics API library for Lemmy v1.0 support. This is a major, ground up rewrite, and I'll add more granular support for unauthenticated requests.
[edit] I could also temporarily disable the block while viewing the blocked content, and re-enable it when leaving. I can look into this as well.