There’s more grey areas in car insurance than 50 shades of grey. The vast majority of people are oblivious to the minor things you are “supposed” to declare and drive round unaware that they could have there insurance void if in an accident. Even just things like remaps, tuning boxes or chips, tinted windows/glass even factory spec things like upgraded alloys or sat navs etc you could go on about the things that insurers say you have to tell them about but nobody ever does
They ask if you have modified the vehicle in any way, so its quite clear they want to know, I have never heard anyone think they don't need to declare chips etc
There are plenty of insurers that charge minimal amounts for some of the mods you listed, once you start using chips etc thats different.
The majority of insurers take the car as base as its delivered from the factory (so dealer fit options would be mods), but thats not a hard and fast rule, some take it as the base spec so even factory options need to be declared.
How you know this for a 10 year old car, well its still your responsibility to check, and they pretty much always point this out as well with a comment along the lines of "if you are unsure you should seek professional advice"
The key boils down to materiality pretty much. A minor prang they won't care, get involved in something nasty and they will.
What actually happens in practice is that whilst technically void they will still honor your insurance in regards any third party liability, but they will then go after you directly for damages, via court if necessary.