Upgrade advice Buster to Bookworm?

I assume a clean install is the best way to upgrade, but is there an easy method to migrate all the software settings that I painstakingly created in Buster? I really don’t want to have to setup AdGuard in particular from scratch again.
(Running Buster v.8.24.1 on Rpi 4b.)

You can update the current system within 2 steps. Both updates are described on our blog

Upgrade to Bullseye DietPi - How to upgrade to "Bullseye" - DietPi blog
Upgrade to Bookworm Debian Bookworm has been released – DietPi Blog