There are three things I would look for. First, that the circuit traces and connections are spaced far enough for the voltage rating. If it is rated 600v the traces need to be more than 3mm apart at least. That is not a real spec but a rule of thumb. Secondly there should be a current limiting resistor of some rather large size, a PTC to further shut things down should there be problems, and ideally a good sized MOV or spark gap device.
Now I am willing to bet that all of these will not have an MOV or spark gap device. I do not expect any pocket meter to be really safe for anything other than CATII/300V. Even if it is rated higher, it is not to be trusted without the proper third party certifications. These are mostly $20 pocket meters of course but if they claim a certain level of safety they better provide it!
If they have current ranges, then they need another whole level of protection because the leads are fixed and only the selection on the dial is responsible for the correct setting/connection. I sincerely doubt, 100% sure, that any of these pocket meters have the correct fuses and protection inside to allow anything that any CAT rating requires. Fixed leads, pocket meter construction, a current measurement range, and the temptation to use the meter at hand when faced with a impromptu situation is a recipe for a exploding meter and a badly injured hand, at least. Fixed lead meters should not have current ranges.......