Tickets will be the biggest hurdle - maybe even more so due to Covid. If you get a membership, you’d probably be able to pick up home league cup and FA cup games (early rounds) but in reality if you’re travelling from Germany, you travel for a match of some importance - Either a CL game or a big PL encounter (hard to get hold of the latter!). Might mean you just need to throw lots of cash at it and get one of these packages sold by third parties.
I assume there’s some Berlin based or German based LFC fan club/group? I’d get chatting to people local to you, you might come across someone that has a good connection that can access tickets. I’ve been to a few away PL games through friends who have season tickets (in the south, where I now live), but generally have to forgo any home ticket available as they’re always on short notice for me to head up to Anfield.
If a Bundesliga club gets drawn in our CL group next season, see if you can get an away ticket through that route. Then put feelers out for a swap - every CL game I’ve been to at Anfield over the last few years I’ve always been within earshot of an away fan in the home seats - and you know fine well an away fan would bite your hand off to go join fellow away fans over sit amongst reds (although I’ve never seen any away fans in the home end receive abuse on an Eurpean night).
In terms of where to stay - depends how long you’re gonna hang around Liverpool for. But I’d opt for somewhere with easy access to the city centre over easy access to Anfield - you can just get a cab to the ground 3-4 hrs before kick off (no mega traffic then) and soak up the atmosphere and build-up (esp if its a European night).
I hope you get to make the trip soon mate!
PS - Berlin - what a city to live in - in my Top 3 fav cities.