I like the idea of pop rivets, but:

The stack height is about 19.5mm, so you’d need a 25mm+ rivet. Not sure how easy it is to find those, or the tool to set them.

Also, only the round hole (5mm) works for rivets. The rectangular one (3×6mm) is too narrow. So you’d be relying on a single rivet. And still probably need a cable tie for the second hole.

Plus, a rivet could be removed and re-riveted with little trace. So it’s not really tamper-evident.

And yeah, it requires a special tool. Another thing to buy, if you don’t already have one.