According to that logic you would have to be afraid of pretty much anything and everything. Which is not worth the diminished quality of life. Minuscule risks can be accepted with ease.
You’d either have to cook sufficient amount of suitable primary explosive (I’d go for PETN myself), or source detonators.
Which says “a piece of common plastic explosive was misplaced and found”. Nothing more but also nothing less.
What would it be? Most common stuff is the C4 and similar. Anything else is rare to encounter. Mainstream explosives are fairly insensitive these days, the days of the dynamite are long gone.
You can get worse stuff from a 4th-July petard. The flash powders are awfully static and friction sensitive.
