Managing the SD card would be on me. As for OS installation, I see that this topic conveniently pops up after my post(s). The buttons must be the key to activate the bootload OS installation SD card on smartphones.
Frankly mentions that the process may include 20 - 30 minutes, plus 32 GBs of disk space. I don’t think the Librem 5 could handle any more material given its said 32 GB disk space in its internal storage compartment. The external storage can help contain and manage files to a degree.