For snacks... I would say it depends how much faff is off-putting. You could have anything, in theory, but my experience is that any food/insulin calculation carries a degree of ’frustration risk’, so my go-to nibbles tend to be things I can have without generally needing an extra dose. A handful of nuts generally does it for me.
The snag with the ‘just dose for anything’ approach is that the more doses you have, the more you risk stacking insulin on insulin and getting unpredictable results. So it can be done, but it’s not all that easy, and won’t always work the same.
Others like to have things like hard boiled eggs, chunks of cheese, olives, a bit of cold meat etc. Dark chocolate (85% or so) can be good too, because you get a proper cocoa hit from only a square or two, without lots of sugar. Having said that, when I do fancy chocolate (or cake... or biscuit...) I just dose and go for it, or combine it with an activity that I know will drop my BG like brisk walking or something else physical but not too intense.