Why not a really dead simple L2 that only runs an amm but it’s an L2 in multiple chains. If it’s sequencer fails to include a tx that’s locally posted, a local implementation of the amm takes over the root in exit mode and local coins can exit.

Or maybe have cross-chain messaging/bridging protocols like Wormhole as an L2?

It could be used to swap eth to sol, stuff like that.

Could def have a rollup with a validating bridge to “settle” to multiple chains (rollups should start doing this imo), but will need to pick one layer for DA that the chain follows So using the other bridges not from the DA layer will just have an added trust assumption