/boot to small, what can I delete, what can I do besides a resize?

I am trying to run apt upgrade. However, I get:

...
E: mkinitramfs failure zstd -q -1 -T0 70
update-initramfs: failed for /boot/initrd.img-6.2.0-26-generic with 1.
dpkg: error processing package linux-firmware (--configure):
 installed linux-firmware package post-installation script subprocess returned error exit status 1
Processing triggers for initramfs-tools (0.142ubuntu2) ...
update-initramfs: Generating /boot/initrd.img-6.2.0-26-generic
I: The initramfs will attempt to resume from /dev/dm-2
I: (/dev/mapper/kubuntu--vg-swap_1)
I: Set the RESUME variable to override this.
zstd: error 70 : Write error : cannot write block : No space left on device 
E: mkinitramfs failure zstd -q -1 -T0 70
update-initramfs: failed for /boot/initrd.img-6.2.0-26-generic with 1.
dpkg: error processing package initramfs-tools (--configure):
 installed initramfs-tools package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
 linux-firmware
 initramfs-tools
E: Sub-process /usr/bin/dpkg returned an error code (1)

which I understand means my /boot partition is to small (seriously even on 18.04 which was originally installed on the machine there was no reason to have so small defaults).

ls -a /boot gives:

.                        config-6.2.0-26-generic  initrd.img                   initrd.img.old      memtest86+ia32.efi  System.map-6.2.0-25-generic  vmlinuz-6.2.0-25-generic
..                       efi                      initrd.img-6.2.0-25-generic  lost+found          memtest86+x64.bin   System.map-6.2.0-26-generic  vmlinuz-6.2.0-26-generic
config-6.2.0-25-generic  grub                     initrd.img-6.2.0-26-generic  memtest86+ia32.bin  memtest86+x64.efi   vmlinuz                      vmlinuz.old

what files could I safely remove? What are my alternatives. This is my work machine, I would prefer not going down the reinstall path. There do not seem to be any old kernels.

This is the output of df

Filesystem                       1K-blocks      Used     Available Use% Mounted on
Ftmpfs                              3270244      3708       3266536   1% /run
/dev/mapper/kubuntu--vg-root     854849916 460936916     350415324  57% /
tmpfs                             16351208       460      16350748   1% /dev/shm
tmpfs                                 5120        16          5104   1% /run/lock
/dev/sda2                           719936    499616        167856  75% /boot
/dev/sda1                           523248      6216        517032   2% /boot/efi
tmpfs                              3270240      1984       3268256   1% /run/user/1001