If buying tamper-tempting devices online (e.g. powered USB/Thunderbolt docks with access to keyboard/mouse/video), you can order several devices from multiple vendors and look for unexpected delays or routes in shipment progress. Requires some experiments to determine baseline "normal" routes and latency.
For post-delivery tamper deterrence, ship via package receiver and audit home door/window locks, https://news.ycombinator.com/item?id=31856444