It is always worth checking that their response was not classified as spam or rejected as spam by your mail service provider / mail client software.
For any company that I deal with I would apply the same approximate strategy: ask, give them a reasonable time to respond, follow up if no response.
I’m not sure that asking Purism is the best approach for that. Maybe latch onto this topic: How knowledgeable do I need to be to operate the Librem 5 for basic needs?
You would need to identify what your “basic needs” are - because they may differ from those of any other customer.
If you hunt around on the Purism web site, you can probably find some demonstration videos of the Librem 5 in use.