If that means that the Librem 5 is configured as a hotspot and it is displaying a QR code so that clients can connect to the Librem 5 as hotspot then I wouldn’t bother with implementing that because the Librem 5 can either already do that or will be able to do that.
On the other hand if that means that the Librem 5 is configured as a WiFi client and it is displaying a QR code so that other would-be WiFi clients can connect to the same WAP that the Librem 5 is connected to then beware the security issues but OK.
If you are going in the direction of creating QR codes then I would suppose that for starters you should have GUI to solicit the information needed to create a valid QR code for each of the types of QR code that you support scanning of. (That would be without plugins and definitely before getting to custom QR codes.)
In other words, right now you have decode of: mailto, mecard, geo, tel, smsto, http, https
So I am suggesting that you add encode of those options.
And also add decode and encode of wifi:
Business card QR codes come in two overall types, web links (URLs) and real business cards, and within the latter type they come in various formats. For example, I just picked one web site at random and their business card decodes as BEGIN:VCARD …
Aside: Web link business cards look like the latest privacy scam from the web. I’m not suggesting that a site offering such a service is actually a scam but I can see where that would be going … (if anyone wants to pursue that comment, please fork the topic)
There are no real standards for most of this.
See also an earlier discussion starting at Camera development progress - #106 by irvinewade
That earlier discussion mentions sms: