8bit I/Q definitely can be used for WiFi. I used HACKRF to send and capture Wifi packet without an issue (offline, use Matlab to process the captured I/Q samples).

Low resolution I/Q (8bit) will impact the RX sensitivity and TX EVM, but it won't be a factor that will totally fail the WiFi implementation.

The HackRF One uses a series of up/down converters, plus a MAX2837 for tuning, and a MAX5864 for the actual ADC/DAC. It goes 22 MSPS, so it can theoretically look at any ~20 mhz section of the 1 MHz - 6 GHz tuning range.

WiFi channels are generally 20, 40 or 80 MHz, so the latter two are not possible given the hardware, and the smallest (20 MHz) would be right at the limit of the hardware. Additionally, there may be other complications (tx/rx switching speed, tuning speed (I'm not sure if wifi would need to do frequency hopping, and if the bandwidth is sufficient to mitigate that need), etc...)

And then someone would have to actually implement it.

Sadly from my research of cheap and hobbyist SDRs, you generally aren't gonna get high bandwidth. I have a limesdr-usb sitting around which supports ~60mhz bandwidth iirc which wasn't good enough for a specific application I looked at which required a channel width up-to 192mhz. Although I'm also an absolute RF noob, do I may have misinterpreted something.

tx/rx switching speed is easy enough by just having two units. Use separate antennae so one doesn't fry the other.

Also just for safety's sake, twiddle your receive preamp gain down before transmitting. That can be done very quickly. Could probably tie a line between the two and have the CPLD do that, actually.