Kids today don't appreciate that in the 1990s, if you wanted a bootable business card (BBC), you had to satisfy yourself with a CDROM, cut to "business card" form factor, which would boot, but
you had to supply your own computer.
Immortalised as the Linuxcare BBC:
https://archiveos.org/lnx-bbc/
(@schoen here, among others, will be ... extraordinarily familiar with this.)
Hilliard's solution here is the 2020s variant.
This is also a testemant to the fact that it's not just ICs which are now cheap (as opposed to, in the 1990s, static data archives), but entire SoCs.
The main limitation is now power supplies, though the prospect of parasitic OTA power extraction is becoming a possiblity, perhaps also thin-film PV and small-scale power storage systems.
Which means that peel-and-stick computing is well within reach, if not a present reality. I suspect Hilliard's BoM would fall by 25-50% in bulk, and given technological advances, should be halving every 18-24 months, which means that $1.50 systems are available now, $0.75 in roughly two years, and only a few more halvings before the 1995 Dilbert Unix user advice, "here's a nickle, kid, get yourself a better computer", will be a practical reality:
https://assets.amuniversal.com/6b08abb09fbb012f2fe600163e41d...
Applied to packages, this means that shipments can report their own progress. Applied to a vehicle, these will permit covert tracking on the cheap. Applied to arbitrary surfaces, indoors or out, surveillance of a given location (audio, video, or other sensors). RFID tags will give way to fully-capable computers, integrated into inventory and pricing stickers. Applied to a drone or glider, an integrated surveillance-and-flight-control package (combine with very small body and lightweight electric motors for power-gliders deployable en masse, not individually threats, but capable of close-up, large-scale monitoring and guidance for more capable systems). Applied to windows, tapping of conversations inside. Likely tapping (or hacking) into available wireless comms nets.
The devices will be well within reach of white hats and black, as well as numerous shades of grey.
Decreasing costs mean that activities not presently viable, many of which won't benefit the common weal, will come into viablity, much as email, fax, pop-up, and phone spam over the past three decades.
Power, sensors, and antennae are likely the biggest limiting factors at this point, though all are also rapidly miniaturising.