well I can’t write a shopping list in Louisiana French yet, but I do have some headcanon worldbuilding around languages spoken in the One Piece setting:
(feel free to use these concepts in your works!)
first up is Seatongue
- the “lingua Franca” of the sea, spoken by almost all seafaring people. also the language of the World Government (but see below)
- roughly equivalent to English, especially because it borrows heavily from dozens of seafaring languages
- Chopper, Nami, and Franky’s first language and in general the language spoken among the Straw Hats
Celestial
- the language of the Celestial Dragons, descended from the language on the Poneglyphs but not at all mutually intelligible with it
- roughly equivalent to a hyper-purist form of “colonial English”
- rarely used any more even among Celestials because Seatongue is just more convenient. However, World Government laws are written in it and the Reverie is conducted in it
- the first language of the Donquixote family and of Sabo
Façon
- roughly equivalent to French: a language associated with food, art, music, sophistication, and really fucking brutal violence
- Zeff's first language is a dialect of this that is roughly equivalent to Lousiana/Cajun French called Façon Nousaut. Nousaut is the language spoken in the Baratie kitchens, and Sanji considers it his "true" native language (he speaks it at a native level because he learned it as a child, but his first language is auf Norden--see below)
auf Norden
- the native language of Germa and of several neighboring nations
- roughly equivalent to German--a harsh-sounding language associated with war and brusque severity, but very complex and actually quite beautiful if spoken with the right attitude
- shares roots with Celestial, which bolsters Judge's claim that his family are Dragons
- the first language of Brook and of the Vinsmoke family
Kalaam
- the native language of Alabasta and neighboring nations
- roughly equivalent to Arabic--a vowel-heavy language and a common source of loanwords that have to do with math, science, and philosophy
- the first language of Yasopp and of Vivi (although they speak wildly different dialects of it). Usopp grew up speaking Kalaam and Seatongue equally
Wanogo
- the native language of Wano and of nations descended from it, such as Shimotsuki
- roughly equivalent to Japanese-- a language with lots of fine distinctions of formality and nuance which is mainly written ideographically
- associated with poetry and craftsmanship. also associated with a certain "foreign-ness" among many other people, mainly due to Wano's long isolation
- due to Shimotsuki's long heritage of swordsmithing it is traditional to name swords in Wanogo, whether or not the smith actually comes from a Wano-descended nation. some may call this a deeply cynical marketing ploy, but....
- Zoro's native language
Norður
- the native language of a few nations in the North Blue
- vaguely related to auf Norden
- roughly equivalent to Icelandic--spoken by very few people, with a vocabulary that relies heavily on coinages and eschews loanwords
- the native language of Sora and of Law. Sanji dimly remembers a few words of it
- Law's dialect of Norður is nearly extinct, and his accent seems weird to most other speakers
Piscine
- the native language of Fishmen and merfolk
- no equivalence among spoken real-world languages
- relies heavily on gestures since sound gets distorted easily underwater. also features an array of clicking and whistling sounds
- some say that Piscine outright can't be spoken with a human mouth
- "Piscine" itself is the Seatongue word for the language. the word for Piscine in Piscine is, appropriately, a gesture
- Jinbei's native language
(quick angst addition: the tradition of naming high-end weapons in Wanogo is why Judge named his offspring in that language despite Germa’s native language being auf Norden)