Compile the actual WireGuard kernel module. Most certainly you want this enabled, unless you're doing something strange.

Packages describing “module” as local USE flag

Package “module” Flag Description
net-vpn/wireguard-modules Compile the actual WireGuard kernel module. Most certainly you want this enabled, unless you're doing something strange.
sys-kernel/aufs-sources Patch kernel to allow aufs being build as a module.
dev-util/unrpyc Build un.rpyc module for run-time decompiling
sys-apps/smc-sum Install Supermicro's kernel module.
virtual/wireguard Compile the actual WireGuard kernel module. Most certainly you want this enabled, unless you're doing something strange.

All packages providing a “module” USE flag (2)