I actually already do something like this based on the #app SMS to URL forwarder (f-droid.org/packages/tech.bogo…). The URL corresponds to a very simple endpoint (a CGI written in Bash!) that receives the SMS details and resends it to a #XMPP MUC.
My use case is that I have a mobile phone with an overseas SIM card that I keep at home while I want to know when it receives a SMS.
So having this functionality as part of #Conversations_im would be great.
SMS to URL Forwarder | F-Droid - Free and Open Source Android App Repository
simple incoming SMS to URL forwarderf-droid.org