Hello, Welcome to the forum.
I’m afraid there is some bad news, root-access is no longer supported (Permanent monitoring system: how to schedule solutions sync with a remote server - #15 by tatiana.andreeva)
so I wouldn’t count on replacing binaries (unless you want to do some more heavy hacking), I think your best bet is to look at an external unit to perform the rtklib calculations (but probably you chose the M+ not to have an external board…). Technically you should be able to start your version from ssh, but I’m afraid that running your own RTKLib on the device is a challenging quest. Also, Emlid is using it’s own modified version of RTKLib, so you won’t be able to have the fixes/changes they did specifically for their devices.
That said, you mentionned the purpose is orientation, for that you could use the onboard IMU. Unfortunately there is no integration within reachview and it is not officially supported. However there are various threads on the forum with starting points.