Here is a picture from an open top bus tour of Hanover in 2024. It shows an array of languages available for the recorded commentary. All the usual suspects are there, but the final channel (12) is unusual.
Channel 12 is for Platt (Plattdeutsch), the collective name for a collection of German regional dialects spoken (and occasionally written) across much of northern Germany. As the official language of the Hanseatic League, it was spoken around the Baltic Sea from around the 14th century to the early 16th century.
Local dialect names for Plattdeutsch include Plattdütsch, Plattdüütsch, Plattdütsk, Plattdüütsk and Plattduitsk.
Low German has some protections under the European Charter for Regional or Minority Languages. The European Charter for Regional or Minority Languages
Further reading
The West Germanic Dialect Continuum, William D. Keel in The Cambridge Handbook of Germanic Linguistics, edited by Michael T Putnam and B Richard Page (2020)
The Germanic Languages (Carol Henriksen andJohan van der Auwera) and Old and Middle Continental West Germanic Languages (Marijke J van der Wal and Aad Quak) in The Germanic Languages, edited by Ekkehard König and Johan van der Auwera (1994)
North Saxon (Reinhard H Goltz and Alastair GH Walker), Westphalian and Eastphalian (Martin Durrell) and East Low German (Helmut Schönfeld) in The Dialects of Modern German: a Linguistic Survey, edited by Charles VJ Russ (1990)
A History of German: what the past reveals about today’s language, Joseph Salmons (2012)
Institut für Niederdeutsche Sprache https://ins-bremen.de/das-ins/
Sprechen Sie Platt? Für Nordeutsche and solche, die es noch werden wollen (2011, licensed edition, Tosa Verlag, no author named) [Do you speak Platt? For North Germans and people who still went to become North Germans]