There were a couple of simple attempts to create an SMS-XMPP bridge that could be of use to this project.
Note that this feature is under consideration by Conversations: https://codeberg.org/iNPUTmice/Conversations/issues/225
What MAXS does and Conversations might do is out of scope for slidge. There is a SMS bridge using the VoIPMS service at https://codeberg.org/boxedtoast/slidgevoipms
There is another approach by debacle here: https://sms4you-team.pages.debian.net/sms4you/ I think they mention they may to write it as a slidge module someday.
I'm closing this, feel free to open a new ticket in slidge-plugin-ideas.