From my perspective it’s totally different products in widely different price brackets, with quite different primary use cases.
In my case, I swapped a Tonex One (without a screen) and a HX Stomp (with a minimal screen) for a Nano and it does the same things that I wanted in a more appealing package. Where I’m at, a QC Mini would have cost me almost three times what I paid for the Nano, so that’s important to me. If I could, I’d of course opt for the QCM, no competition. But given budget and use case (able to power via USB-C or via small 9V supply) it’s a functional product IF you can stomach the lack of screen. I find it totally okay since the app is not a piece of shit that hurts your eyes like some others I’ve tried (Mooer P1 for example).