I recently found a project that contains several thousand MIBs, all located in a single git repo.
https://github.com/hs-cx/snmp_mib_archive
It might be handy to look at pulling and integrating those MIBs, or to possibly have a script included in the LibreNMS install that pulls the archive in and installed all of the various MIB files into itself.
I know this will not provide graphs, or information on what to probe, but it’s a first step towards having broader coverage of devices.