The core ideas seem quite similar to what I wrote in Cross-rollup NFT wrapper and migration ideas !
Allowing NFTs to be issued in any domain (L1 or an L2 rollup) by pre-allocating some indices to each domain is an excellent idea and definitely needed to prevent confusion from multi-allocation.
The main challenge with using cross-messages directly is that many of these rollups are optimistic rollups which have a 1 week withdrawal delay. This is okay for some exceptional situations (eg. a particular rollup is shutting down completely due to some governance operation, and everyone is getting their assets out), but it’s really inconvenient for normal use. Hence why my proposals make wrapper NFTs accessible instantly, and not just after a week-long wait.
Another issue is that I think it’s not just L1 ↔ L2 transfers that we should be thinking about, but also L2 ↔ L2 transfers (eg. Optimism ↔ Arbitrum). These L2 ↔ L2 transfers should not require directly touching L1.