Joplin has a data API that is suited to fetch and create notes. If you want to use python, there is a wrapper with some examples.
Not sure how the interface of Odoo looks, but probably there could be a glue script to do the synchronization between Joplin and Odoo.
Limitations:
- The data API works only for desktop clients. AFAIK the server can't be accessed with an API. See Does Joplin Server have the API - #9 by zblesk.
- It won't be "the same" synchronization as Joplin uses internally, since you would have to implement the logic in the script.