Bitcoin = Settlements Layer (L1)

Electrum Server = Accounts Layer (L1.5)

Lightning = Payments Layer (L2)

RGB = Contracts Layer (L3)

Fedimint = Banking Layer (L3)

Nostr = Social Layer (L3)

Carbonado = Storage Layer (L3)

Sidechains are not layers, they're separate blockchains. Layers show us, we only really need the one blockchain.

I'm not concerned about scaling. Plenty of these layers can scale themselves, but that will take work. It's time to build.