From my point of view, it's a question of balance and you have to find the right compromise between security or convenience.
HardenedBSD was born out of his interest in security and as a result we have issues to deal with that freebsd does not.
Keep in mind that no system is infallible, the goal being to make the attackers lose as much time as possible in order to make them abandon. But if you come across an attacker who has made it his life's ultimate goal to hack your system, he will succeed sooner or later...
As is often said, the first security flaw is the interface between the chair and the keyboard... A hardened operating system will do you no good if you leave a post-it note of your password stuck on your computer ^^
For hardening, there is no ultimate guide even if the governmental CERTs recommandations are close to it, the guides often become obsolete very quickly, it is necessary to continualy search and test to see if your system remains sufficiently usable to your taste (so that it does not simply look like a typewriter).
Example of a guide for Linux that I like and which many points can be used for *BSD:
https://www.ssi.gouv.fr/en/guide/configuration-recommendations-of-a-gnulinux-system/For the tuning:
https://calomel.org/freebsd_network_tuning.htmlhttps://web.archive.org/web/20210910153326/https://calomel.org/freebsd_network_tuning.html