NB6G I am a supporter of the open IM protocol, and I have also participated in XMPP-related project development in the past. In comparison, the Matrix protocol is quite complex.
In the amateur radio field, some software (such as GNU Radio) uses Matrix as its primary communication channel.
In the UK, someone with the callsign M0AWS established a Matrix server and several groups specifically for HAM users, and conducted simulations/digital radio network experiments involving the intersection of Matrix and HAM communities.
Recently, an open-source project called "Matrix-RF-Bridge" based on RTLSDR has also emerged in the community. Those interested can explore it.