The same would be true for the header files as well.

Ok, done! Thanks again to both!

I will now mark this as solved.

You need to target chimaera-backports for that package, just as you did for the individual kernel package.

I learned something new today.  I will install it now so my kernel does not get left behind on the update process. 

Thanks HOAS.

Edit:
migf,
The same would be true for the header files as well.

Thanks for your tip: I have now the backported metapackage.

I found out that linux-image-amd64 was already there and when I tried to reinstall it apt answered that the 5.10 kernel would be installed; so
I quit.

You need to target chimaera-backports for that package, just as you did for the individual kernel package.

The backported metapackge is needed. You will soon be running an outdated kernel with known vulnerabilities if you don't install it.

If I may put a related question: I am getting this in dmesg concerning the firmware of the Radeon GPU:

 [drm:amdgpu_pci_probe [amdgpu]] *ERROR* amdgpu requires firmware installed
[    3.067618] amdgpu: See https://wiki.debian.org/Firmware for information about missing firmware

Is there also a package for it, and is it recommended to add this firmware?

Thanks again!

Then you may uninstall the default kernel if you wish, after a reboot of course.  The reboot should boot the new kernel, and you can verify this by running - after the reboot,

I added the backports line to the apt sources.list and I just found out I missed "non-free" there, but I think this will not change what I describe below.

@Head_on_a_stick: I found out that linux-image-amd64 was already there and when I tried to reinstall it apt answered that the 5.10 kernel would be installed; so
I quit.

@nixer: I tried to install linux-image-5.18.0-0 as you suggested but there are several packages that match this name:

# apt-get install -t chimaera-backports linux-image-5.18.0-0
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Note, selecting 'linux-image-5.18.0-0.deb11.4-rt-amd64-dbg' for regex 'linux-image-5.18.0-0'
Note, selecting 'linux-image-5.18.0-0.deb11.4-amd64-unsigned' for regex 'linux-image-5.18.0-0'
Note, selecting 'linux-image-5.18.0-0.deb11.4-amd64' for regex 'linux-image-5.18.0-0'
Note, selecting 'linux-image-5.18.0-0.deb11.4-amd64-dbg' for regex 'linux-image-5.18.0-0'
Note, selecting 'linux-image-5.18.0-0.deb11.4-cloud-amd64' for regex 'linux-image-5.18.0-0'
Note, selecting 'linux-image-5.18.0-0.deb11.4-cloud-amd64-dbg' for regex 'linux-image-5.18.0-0'
Note, selecting 'linux-image-5.18.0-0.deb11.4-rt-amd64-unsigned' for regex 'linux-image-5.18.0-0'
Note, selecting 'linux-image-5.18.0-0.deb11.4-rt-amd64' for regex 'linux-image-5.18.0-0'
Note, selecting 'linux-image-5.18.0-0.deb11.4-cloud-amd64-unsigned' for regex 'linux-image-5.18.0-0'
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 linux-image-5.18.0-0.deb11.4-amd64 : Conflicts: linux-image-5.18.0-0.deb11.4-amd64-unsigned but 5.18.16-1~bpo11+1 is to be installed
 linux-image-5.18.0-0.deb11.4-amd64-unsigned : Conflicts: linux-image-5.18.0-0.deb11.4-amd64 but 5.18.16-1~bpo11+1 is to be installed
 linux-image-5.18.0-0.deb11.4-cloud-amd64 : Conflicts: linux-image-5.18.0-0.deb11.4-cloud-amd64-unsigned but 5.18.16-1~bpo11+1 is to be installed
 linux-image-5.18.0-0.deb11.4-cloud-amd64-unsigned : Conflicts: linux-image-5.18.0-0.deb11.4-cloud-amd64 but 5.18.16-1~bpo11+1 is to be installed
 linux-image-5.18.0-0.deb11.4-rt-amd64 : Conflicts: linux-image-5.18.0-0.deb11.4-rt-amd64-unsigned but 5.18.16-1~bpo11+1 is to be installed
 linux-image-5.18.0-0.deb11.4-rt-amd64-unsigned : Conflicts: linux-image-5.18.0-0.deb11.4-rt-amd64 but 5.18.16-1~bpo11+1 is to be installed
E: Unable to correct problems, you have held broken packages.

What is the one to be selected?

Installed the necessary firmware:

Add the backports line to the  /etc/apt/sources.list  file

Then:

apt update

Install the backported kernel:
apt install -t chimaera-backports linux-image-5.18-(whatever the version is in backports).

Might be best to install the kernel before the firmware.

It appears that this firmware-realtek package may support your RTL8852 card.  From the debian package page showing supported hardware:

I already tried some solution I found out in the Debian site, the result being that I had to reinstall everything from scratch,
and I am aware of the driver in [https://www.amd.com/en/support/graphics/radeon-rx-vega-series/radeon-rx-vega-series/radeon-rx-vega-64] that seems to still have issues.

So I think there may be two more easier solutions

• install a more recent kernell like 5.18 and stop using the one in the Chimaera distribution: will this solve the problem, and is it a safe solutiom?

• keep the current kernel and buy a dongle that is known to work with it: what such dongles are there?

I will be very grateful for any help on this!