Discussion on: What is the best .zshrc config you have seen?

The project says it's a drop-in replacement for powerlevel9k

Not quite. Here's what it says:

Powerlevel10k can be used as a fast drop-in replacement for Powerlevel9k.

• Fast: Powerlevel10k is over 10 times faster than powerlevel9k when using the same configuration options.
• Can be used as a drop-in replacement rater than is a drop-in replacement: Powerlevel10k has many extra features not found in Powerlevel9k.

[powerlevel9k is] still active as far as I know

I guess this depends on one's point of view. Commit activity graph shows last commit in March.