We did the groundwork for this with the ultra-low-bandwidth Matrix stuff last year: https://matrix.org/blog/2019/03/12/breaking-the-100-bps-barrier-with-matrix-

We did the groundwork for this with the ultra-low-bandwidth Matrix stuff last year: https://matrix.org/blog/2019/03/12/breaking-the-100-bps-barrier-with-matrix-meshsim-coap-proxy/ https://matrix.org/blog/2019/03/12/breaking-the-100-bps-barr.... But frustratingly nobody has picked up that work yet.