I may be 2 months late, but I've got a concept for a relic pack. I wanted to make it myself, but I'm also making a resource pack, so I want to focus on that. I have a list of relics, their features, and the structures attached to them, and I could also make textures for them. :-) Some examples:
Piglin Crown: Gold, quartz, and netherite crown. Rarely found in Bastion chests, and greatly decreases Piglin Brutes' aggro range.
Chorus Harvester: End stone axe stained with chorus. Found in end cities and in underground Enderman lairs. Allows the collection of chorus flowers when chopping down a chorus tree (they normally do not drop unless you break them directly)
Alpha Blade: Has stone, iron, and diamond variants, using the pre-1.14 style. Found in an Alpha Ruin (one per world) as a stone sword, and can be upgraded at a smithing table with the respective resource blocks. It has the same swing speed as pre-1.9, and breaking grass or leaves gives Alpha variants with the original bright green shader.
>Alpha Ruins would be generic, destroyed houses made using only resources available in early Alpha, and would be surrounded by Alpha foliage.
I have more ideas already written down, and I'm certain I'll come up with more. :-)