How to build a Nether portal in Minecraft (and link two portals)
The Crying Obsidian around them does not work in a frame.

Crying Obsidian is obsidian that weeps purple drops and gives off a dim light.
It cannot be crafted; it can be found in chests. It is mined with a pickaxe (at least tier diamond). It gives off light level 10.
It needs a diamond pickaxe like obsidian and is just as resistant. You find it in ruined portals and bastions, or get it from piglin bartering. It is the main ingredient of the Respawn Anchor, but it cannot be used to build a Nether portal.
This item has no crafting recipe.
The Crying Obsidian around them does not work in a frame.
Mining the block drops it. It can be found as loot in Bastion Remnant. Bartering: Piglin.
It is the key material of the respawn anchor. It is an ingredient in one recipe: Respawn Anchor.
The fastest tool is the pickaxe. It needs at least a diamond pickaxe.
Yes, light level 10.
Placed under a Note Block, Crying Obsidian gives the Bass drum sound.
No: pistons cannot move it.