@firstname.lastname@example.org There are only Librem5 with bm818 around. The other modem is not available as far as I understood. There is said to be one phone in the hands of a developer that has a built in Gemalto PLS8 as originally announced as an option to the bm818.
If I understood correctly a big problem with the Gemalto modem is that one could make it completely unusable inside the Librem5 by issuing a certain AT-command switching the data connection to something that is not connected inside the Librem5.
Would be a big support problem for Purism.
Anyway I'd prefer to get a Gemalto modem, but it seems the option is not available anymore.
Your Librem5 contains a bm818 :).