Zen is pretty much just the plain firefox hardening settings (check the privacy page on the e zen website). Librewolf and other hardened forks do a few more things than plain firefox (at the risk of breaking websites).

Of course even plain firefox is better than chrome, add ublock and a custom dns (nextdns or self hosted pihole/technitium) and you should be all good against most things.

Saying this as someone using zen with ublock and self hosted dns, so I might be biased 🙂

Some of the customisations librewolf does can be manually applied to ff/zen iirc