Currently there is no native way of retrieving all the threads… as in there is no client.beta.threads.list() function .
However with clever use of metadata with the betaassi framework, it is possible to keep track of threads created. See here for details (openairetro/examples/listablethreads at main · icdev2dev/openairetro · GitHub)
# these primitives are exposed
ListableThread.create(**kwargs)
ListableThread.delete(thread_id)
ListableThread.list()
Because this uses metadata to maintain that list, it is limited by the amount of bytes in the metadata that can be used.