I see, not many guides in my native language either, but I think the respective websites are explaining things well enough and if they don’t have an italian translation available already Google Translate should do the job.
NextDNS is probably your best bet, as it can be setup on your devices or router directly and is not as technical to get started: https://nextdns.io/
For Pi-hole you will need a dedicated device on your network, like a laptop or Raspberry Pi, or a router with custom firmware. On it you install the software, and after that it will basically act as your own instance of NextDNS, and you can point your devices to it for DNS resolution: https://pi-hole.net/
Disclaimer: i am also just getting started with these tools, still in research phase with not a lot of free time to invest in it so if i made any mistakes explaining i apologise, and definitely understand your frustration.
I wasn’t aware of DeepL actually. Google Translate had been my go-to service for a long time so I never searched for another one, but DeepL looks promising , I’ll have to give it a try, and you should certainly use it instead of Google if you know it’s better.