The don't use the same network, and never have. Jami uses OpenDHT (https://jami.net/ces-2019/ https://jami.net/ces-2019/), GNUnet uses its own DHT (see for exam

The don't use the same network, and never have. Jami uses OpenDHT (https://jami.net/ces-2019/ https://jami.net/ces-2019/), GNUnet uses its own DHT (see for example https://grothoff.org/christian/nss2011.pdf https://grothoff.org/christian/nss2011.pdf, or the rather hacky (and not complete) bib page: https://bib.gnunet.org/#DHT https://bib.gnunet.org/#DHT)