Anything with USB-A is neat with this type of device. For example, a LimeSDR USB would work (even a uSDR for M.2, though I'd wait for the successor).

For Kali, I sport a GPD Pocket 2, and that works well, but I'm in the process of switching that to my Hackberry Pi CM5.

Still, I bought that end of last summer. I honestly would not buy any computer right now. The RAM prices are simply insane.

It comes with a good, proven BB keyboard. No option for GPIO pins or gamepad module, but I don't need such anyway. Instead, what I have in it is a USB hub which fits nicely in the side.

Unfortunately, the RPi CM I had lying around were CM4 with eMMC or CM5 w/o WiFi/BT. So I bought a new CM5, with 16 GB RAM. That was end of last summer. I'm not sure I'd bother now, given the RAM prices which surely affected CM5 prices. Actually, I should probably sell those for profit, since they're not doing anything.

[1] https://github.com/ZitaoTech/HackberryPiCM5

You are right though, ive loved tinkering especially some if the cool linux based handhelds but i always come back to mobile/tablet because my limiting resource is time and android/ios kinda just works.