QR code scanning through non-Safari browsers do not provide the possibility to check the link on iPhone

If you use the code scanner (as opposed to the camera) the link is revealed at the bottom of the screen.

Use the Camera Control to open another app on iPhone - Apple Support

There is something about your question I don't understand though. A browser need not be involved in capturing the image. It's just a picture. I don't know even how to use Safari to scan a QR code directly, not without some kind of extension that is. If it did that would be useful. Perhaps I'll learn something.

Thank you for that explanation. I now understand that would like to inspect that link and have an opportunity to determine exactly what it's about to load before DDG or some other browser app opens it, with all the potential for tracking and other privacy-intrusive concerns. At least that's what I assume from the context of your question, and I don't disagree with what you would like to do.

To my knowledge iOS is offering that opportunity more or less as a courtesy, embedded in its inextricable ties to Safari's functionality. It seems likely to me that aspect of its programming is not being offered to other browsers for Apple's selfish needs that they probably are not willing to openly discuss. After all they have to distinguish themselves from the competition somehow, and for what it's worth Safari is already far superior to other browsers in its ability to protect your privacy to the greatest practicable extent. Yes even DDG. Remember DDG's singular advantage over other search engines is that its search terms are stripped of PII before its search queries are transmitted — that's it. The DDG browser app itself is fine, no problem with it, but Safari is still superior to all others as a browser app. Designate DDG as Safari's Search Engine and you will have the best of all possible worlds, at present that is.

Anyway that is more of an editorial comment than a solution, so if you would like Apple to consider implementing what you seek please let them know, here: Feedback - iPhone - Apple. I think yours is a good idea.

I also think browsers aren't going to be around forever. They are way too much a target-rich environment for scammers, they're a security nightmare, they're clogged with advertisements... not an environment conducive to growth. The future belongs to apps. Search engines will cease to be relevant and will die along the way.

You're welcome. I'm glad you found it useful, and I encourage you to file Feedback with Apple. I think it's worthwhile.