These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.62 s (backtrack: 0/20).

[ebuild  N     ] dev-build/b2-5.5.3::gentoo  USE="-examples" 1198 KiB
[ebuild  N     ] dev-libs/libusb-1.0.30:1::gentoo  USE="-debug -doc -examples -static-libs -test -udev -verify-sig" 641 KiB
[ebuild  N     ] virtual/libusb-1-r2:1::gentoo  USE="-udev" 0 KiB
[ebuild  N     ] dev-libs/boost-1.91.0-r2:0/1.91.0::gentoo  USE="bzip2 context nls python stacktrace zlib -debug -doc -icu -lzma -mpi -numpy -test -test-full -tools -zstd" PYTHON_TARGETS="python3_14 -python3_12 -python3_13" 199785 KiB
[ebuild     U  ] net-libs/libpcap-1.11.0::gentoo [1.10.6::gentoo] USE="dbus usb* -bluetooth -netlink -rdma -remote -static-libs -test -verify-sig -yydebug" 1028 KiB
[ebuild  N     ] sys-process/usbtop-1.0_p20220419::gentoo  613 KiB

Total: 6 packages (1 upgrade, 5 new), Size of downloads: 203264 KiB

The following USE changes are necessary to proceed:
 (see "package.use" in the portage(5) man page for more details)
# required by sys-process/usbtop-1.0_p20220419::gentoo
# required by =sys-process/usbtop-1.0_p20220419 (argument)
>=net-libs/libpcap-1.11.0 usb