Edit: as of 12/24/2021, we have learned from dev team member Eric that Shibarium will definitely be an L2, and not it’s own blockchain.
Topics covered below:
Shibarium will be SHIB's version of a blockchain. Ethereum Blockchain gas fees are high, one aspect of Shibarium is meant to fix that. While there will be multiple tokens and projects (unrelated to SHIB) launched on Shibarium, the main aspect Shytoshi has been focusing on is cheaper and faster transactions than Ethereum. Some people feel like Shibarium will be more of a Layer 2 solution for Ethereum. Unfortunately, Shytoshi (and Ryoshi before him) have both taken to calling Shibarium a "L2" while also calling it "SHIB's own blockchain". So, until there's a whitepaper published, we won't know what it actually is. A Layer 2 solution does seem most likely. There are a few existing systems out there that could be what Shibarium is most likely akin to.
Optimistic Rollups:
ZK Rollups:
Side Chains: