Upvote:-2
Italy and Germany are both in the Schengen Zone: Italy has no authority to require visa for certain nationalities, while for COVID-19 pandemics there can be provisions for additional screening or or flight ban from origin (which is not your case, as the flight is scheduled).
Once you cross the Italian border you are crossing the general Schengen border, so the same rules apply to all Member States.
If you are sure that you can visit Germany, you can cross the Italian border.
Since flights from Italy to Germany are domestic, and the same applies to all intra-Schengen flights, there is no such transit visa for passengers directed to a Schengen State. You clear the border only once.
Upvote:3
Based on the link (quoted below) supplied by @mlc, Italy does not require a visa to enter for a UK Travel Document (Blue or Red) holder.
Therefore you can fly to Italy, where you will enter the Schengen Area and then take an internal Schengen flight to Germany.
UK Travel Document - Consolato Generale d'Italia Londra.
Holders of 1951 Geneva Refugee Convention Travel Document (Blue) and Holders of 1954 UN Convention Travel Document for Stateless (Red) issued in Great Britain can travel visa free up to 90 days. For trips longer than 90 days, they are required to apply for long stay visas.