> but seems not much came from the effort

That's been my experience dealing with QCM based devices running linux in the past. Some OEM buys a batch of chips, gets a reference design and an old version of the linux kernel with a zillion out-of-tree hacks and patches that make updates impossible.

I generally advise clients to use rockchip as they have _very_ good mainline support and put any QCM modem at the end of a USB connection so it doesn't hold the product back.