Thank you for you answer. Would doing without districts altogether for federal legislator be a possibility? And on state level you could model on the congress with one chamber based on districts' majority and one other on population?

It's not a near term practical possibility, it would require a Constitutional amendment.

For states, they each get to decide how to structure their own government. Many do have 2 houses. Here the upper house is elected from larger districts than the lower house, but each member represents 1 district.