Kali was built out as a penetration testing distro, though it does contain some diagnostic tools.
Not a bad place to start if you’re used to Debian, but it is a rolling release so it may break unexpectedly, or have new bugs introduced with each update.
A persistent USB with just Debian could have all the same tools installed but have a longer support scope on releases so you don’t have to update daily (bleeding edge) which is nice to reduce read/writes to the flash drive it’s on.
That being said, I keep a Kali live image (persistent) but thats becauae its home - my first introduction to Linux was 5 minutes with Red Hat, but aside from a brief intro in highschool, I really started with Linux in Backtrack, offensive security’s predecessor to Kali.
Yes, I have to learn things the hard way lol.
I started with Backtrack on a laptop, and I currently have Kali on a preserved USB; with endeavor as a daily driver.
That being said, my current “real” daily drivers in Win10, mostly for gaming - Not because proton doesn’t do a hell of a job, it certainly does, but it makes modding single player games more complicated. I will say that is absolutely my fault, I haven’t spent enough time to figure it out. But after work, and the wife, and the animals, and the alcoholic BIL who shares the house… I just want to use Vortex to add some simple QOL mods to single player games and play it.
I troubleshoot IT issues all day at work, at the end of the day, I just need it to work. I’ve hardened and removed as much telemetry type bullshit as I could, but I’m sure some slips out. For my threat model, on this machine, I’m fine with it.
On the aforementioned labtop I boot into Kali for… well, that has a different threat model.
Its all self hosted vulnerable VMs for the specific reason of education, but some activities may fall into a grey area, so better safe than sorry.