I am interested in learning about how "shard chains" work. I'm concerned after reading https://ethereum.org/en/eth2/shard-chains/ https://ethereum.org/en/eth2/

I am interested in learning about how "shard chains" work. I'm concerned after reading https://ethereum.org/en/eth2/shard-chains/ https://ethereum.org/en/eth2/shard-chains/ that sharding is aimed at letting individual dApps roll up transactions -- i.e. the individual app would be the effective shard key -- and thus that would introduce some notion of centralization into the system.