Will sharding affect data or execution? Or both?

I heard things like swapping tokens, doing general things, etc. on Ethereum today are on the execution layer.

While sharding right now as part of the upgrades will only help the data layer. Is this true? Does that mean even after sharding is complete the "base" layer for doing things like swapping tokens (data) will still be somewhat expensive? So sharding only affects L2s? Will the base data layer ever be sharded?