For me it seems that there are still two kernels:
-rw-r--r-- 1 root root 64325755 Jan 23 07:12 initrd.img
-rw-r--r-- 1 root root 64317791 Jan 9 08:14 initrd.img-5.15.0-1-librem5
-rw-r--r-- 1 root root 64325755 Jan 23 07:12 initrd.img-5.16.0-1-librem5
-rw-r--r-- 1 root root 64325426 Jan 23 02:18 initrd.img.bak
drwx------ 2 root root 12288 Sep 11 07:31 lost+found
-rw-r--r-- 1 root root 4900200 Dec 20 17:34 System.map-5.15.0-1-librem5
-rw-r--r-- 1 root root 4941866 Jan 17 11:33 System.map-5.16.0-1-librem5
-rw-r--r-- 1 root root 24610824 Jan 23 07:12 vmlinuz
-rw-r--r-- 1 root root 8762699 Dec 20 17:34 vmlinuz-5.15.0-1-librem5
-rw-r--r-- 1 root root 8815340 Jan 17 11:33 vmlinuz-5.16.0-1-librem5
-rw-r--r-- 1 root root 24610824 Jan 23 02:18 vmlinuz.bak
and the space is not much there:
df -kh /boot
Filesystem Size Used Avail Use% Mounted on
/dev/mmcblk0p1 451M 323M 105M 76% /boot
Here is what my Ubuntu phone has:
phablet@ubuntu-phablet:~$ df -kh /boot
Filesystem Size Used Avail Use% Mounted on
/dev/mmcblk0p6 2.0G 1.6G 389M 81% /