This is a really interesting idea. One question here is where do L2 clients send transactions to, so that searchers / builders can then make up L2 blobs? Are they sent to the L1 mempool, with some special metadata that “informed” searchers can interpret? Is this going to significantly increase load on the L1 mempool (if L2 transaction load is going to be 100x L1 transaction load)? Another possible approach is to let these L2 transactions live in new p2p mempools (one for each L2) that “informed” searchers can then fish them out of.