Are there other ways to reduce gas fees besides L2/Sidechains?

I’ve been trying to do my research on different scaling solutions that will help reduce gas prices. I’m semi familiar with how rollups and sidechains work. But I’m curious if there are any other projects besides rollups and sidechains that aim to be a good scaling solution for ETH. I’ve heard sharding is going to help a ton, which makes sense. I also remember reading something awhile ago about the possibility of L3 scaling solutions for real world applications. Just trying to find out what the Ethereum community thinks about it as a whole