I have yet to find a way to do this on my phone, but on my pc I use the Joplin note taking app with the web clipper extension. Joplin is also available for smartphones, but I don't think the webclipper is.

You can select part of a webpage, or even the whole page, and have it saved into Joplin. You can create notebooks for certain categories or add tags to make searching stuff more easy.

I sync it using nextcloud, but that's a bit more work to set up.

You can unblock from the app:

• browse to the community in question by using the search function
• tap the menu on the top right
• click the block button again (it will say it blocked the community)
• refresh the page

Community will be unblocked.

I don't think there's a list of blocked communities, so you have to know which community it was.