We are probably going to have a story pack soon, which adds more relics. I think it will be kind interesting if we introduce artifacts into the game, they are powerful relic once tipped the balance of universe, wars been fought, legend forged, but they are broken into different pieces in the end. Each piece of artifact is still full- fledged relic on its own, might be a bit weaker than normal relic, but you will gain an artifact action to spend minor artifacts to restore the artifact to its former glory once you completed the set.
And this also is a good time to introduce relic war, every country who owns fragment has wargoal with each other that has same set of fragments. And same as Galatron, everyone would have wargoal with you if you reassembled an artifact. Other relics should have appropriate wargoal too, maybe not all of them, but something like Khan's Throne should have one.
If by any chance, relics are lost during country destruction, they shouldn’t be lost forever. The trade enclaves can hold an auction on their black market if you have a good relationship with them for those lost relic every five years after mid game, maybe add some relic only can be found on the auction, and I think you can also sell your unwanted relic to them.
And this also is a good time to introduce relic war, every country who owns fragment has wargoal with each other that has same set of fragments. And same as Galatron, everyone would have wargoal with you if you reassembled an artifact. Other relics should have appropriate wargoal too, maybe not all of them, but something like Khan's Throne should have one.
If by any chance, relics are lost during country destruction, they shouldn’t be lost forever. The trade enclaves can hold an auction on their black market if you have a good relationship with them for those lost relic every five years after mid game, maybe add some relic only can be found on the auction, and I think you can also sell your unwanted relic to them.