I think I have a very similar issue. Unable to get Wireguard running on an odroid hc2.
Trying to install wireguard-dkms yields to the following output (After pinning debian 11 debs):
user@device:~$ sudo apt install wireguard-dkms --reinstall
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
0 upgraded, 0 newly installed, 1 reinstalled, 0 to remove and 0 not upgraded.
Need to get 255 kB of archives.
After this operation, 0 B of additional disk space will be used.
Get:1 http://deb.debian.org/debian bullseye/main armhf wireguard-dkms all 1.0.20210219-1 [255 kB]
Fetched 255 kB in 0s (2,296 kB/s)
(Reading database ... 68021 files and directories currently installed.)
Preparing to unpack .../wireguard-dkms_1.0.20210219-1_all.deb ...
Deleting module wireguard-1.0.20210219 completely from the DKMS tree.
Unpacking wireguard-dkms (1.0.20210219-1) over (1.0.20210219-1) ...
Setting up wireguard-dkms (1.0.20210219-1) ...
Loading new wireguard-1.0.20210219 DKMS files...
Building for 5.4.243-odroidxu4 6.1.0-10-rt-armmp
Module build for kernel 5.4.243-odroidxu4 was skipped since the
kernel headers for this kernel do not seem to be installed.
Module build for kernel 6.1.0-10-rt-armmp was skipped since the
kernel headers for this kernel do not seem to be installed.
The reason why it is unable to build the module seems to be a mismatch between the linux image and linux headers:
user@device:~$ sudo apt install linux-image-current-odroidxu4
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
linux-image-current-odroidxu4 is already the newest version (23.05.1--Sf984-Db165-P49bd-C3969H6842-HK01ba-V014b-B9c18).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
user@device:~$ sudo apt install linux-headers-current-odroidxu4
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
linux-headers-current-odroidxu4 is already the newest version (23.02.2).
user@device:~$ uname -a
Linux device 5.4.243-odroidxu4 #1 SMP PREEMPT Mon May 22 13:57:29 UTC 2023 armv7l GNU/Linux
Any idea how to fix this?