First of all I don’t know about any other notebook that comes with a pre-installed Linux and full disk encryption.
The patch that adds the password dialogue for encryption of the masterkey for disk encryption into gnome initial setup is maintained in the purism gitlab.
I’d say that the problem for the wifi password is probably the same for Debian Buster (please correct me, I didn’t really try it) and the password dialogue for disk encryption is specific to PureOS.
The design flaw only affects people who do not use an english keyboard and yes, I think it is a real show stopper that has to be fixed alongside with the problem that a fix for a keyboard firmware error in english layout keyboards breaks the keyboard layout for people ordering with a non-english keyboard layout (at least this is what happened when I got my Librem a few weeks ago).
But no, you’re not breaking the encryption by using the wrong layout. If you remember the password you typed you can use any other computer to type it blindly while using an english keyboard layout. What you get on the screen is the password you have to type in.
Furthermore you might need into account
From my point of view (using the german keyboard version of a Librem13v4) I absolutely cannot recommend the notebook with german keyboard layout to anybody without deep and good knowledge of Linux and the willingness to overcome these first obstacles by investing time.
On the other hand I’d strongly recommend the notebook as is to any Linux professional with the hint to this forum and the initial problems.
About the disk encryption and - from my point of view - another design flaw you can read here.
Keep in mind that Purism is taking a lonely way to build something new (based on what already there is) and make the world a bit better. If you expect the polished perfection of Google, Apple, Samsung, Microsoft etc. you’ll have to go on accepting that you’re not owning your data and that your data is exploited.
Taking back control means also taking responsibility.